Critical fix to plugin handling: client modules adding certain plugin types via the panels_include_directory() method were only half functioning.

Due to a foolish way of handling the module name in the first-round implementation of panels_include_directory(), module name information was not being properly recorded in plugins that needed it (layout plugins, esp.). The method of handling module name strings has been changed to resolve this problem.

The editor render callback property allows a content type to define the way it should be rendered in the display editor itself. This is useful if there are circumstances in which you really _do_ need to have the content preview displayed (which, as of beta4, is disabled).

#265908 by Pancho: Reduce the number of icons on the context order arranging page. Use newer icons in place of older ones.

#268480 by smk-ka: Fix to make sure that cached panes still get acted on by hook_panels_pane_content_alter().

#256461: Allow individual panel pane styles. This requires a small modification to existing panel styles so that panel styles don't conflict with pane styles, but it is very minor, and very few panel styles are out there yet.

#270363 by dww: Fixed problem with pane title rendering in the content editor (ternary was backwards).

Also improved readability and added explanatory comment.

Adds checks at various stages to ensure that $pane->shown is set; if it is not, then it defaults to TRUE, instead of FALSE (and therefore hidden).

Updated three content_type plugin properties: "ignore roles" is now "role-based access"; expanded the variables passed to "form control" and "visibility submit" callbacks.

Updated variable names in panels_add_content() to reflect the actual sort of data they're holding - basically, variable naming consistency. Also updated a few explanatory comments.

#262687 by JBrauer. Proper way of handling base_path() for icon images on display content editor, not just a hacky added slash at the base.

#260221 by sun, Pancho. Primarily codestyle cleanup; also fixed some missing leading slashes that were causing the edit icons not to appear in the new helptext for the display editor.

Small fix to get rid of array_intersect_keys(), which was implemented in PHP5.1.0 and therefore screws PHP4 compatibility.

Expanded standard helptext on the display editor to include explanations of the various buttons present in the editor.

Mostly changes to get rid of the big, ugly "Content preview has been disabled" message on panes, and stick that into a less-intrusive body message. Also some code legibility cleanup on calls to panels_ajax_form().

#261797 by Pancho. E_ALL fixes: ensuring that vars are declared as new stdClass() before being used as classless objects. Also some scattered bugfixes here and there.

#258483 by Pancho. No need to declare a var for a subset of $form_values that only gets used once. On the other hand, declaring that var in the validate function won't make it available in the submit function...! Fixed both the validate and submit handlers to use $form_values directly, nice and clean.

Changed show/hide settings to be more in line with the rest of the access control parameters. Part and parcel of that was moving storage of the pane show/hide information into the pane table itself...probably where it should have been from the start.

First round of work & debugging on hide/show panes is complete. In addition to the new js, php callback processor for the show/hide function, and small css changes to make hidden panes stand out as hidden, some residual cleanup from the big api rewrite. Also fixed a bug that was causing the configure form not to work for existing panes. Not sure why, the code SHOULD have worked fine, but...

forgot to finish updating the name changes on panels_allowed_layouts to display_edit.inc; also, inadvertently left a static command intended purely for debugging panels_allowed_layouts when it was first committed.

panels_pane_access() is now the primary handler for the overall panels pane access logic. Depending on settings in the $display object and the content_type of the pane being checked, panels_pane_access() now  may or may not check $display->pane->access, any visibility check callbacks defined by the content type, and can use (what amounts to, but is not exactly) AND or OR logic in evaluating these.

MASSIVE update. Updated, rewrote, and pretty thoroughly debugged the entire add/edit pane config system. Also made the system capable of handling the new expansions to content_type definitions. Numerous other small related changes as well, too many to describe here. Worth noting is that, for the moment, all rendering of pane content previews in the display edit form is disabled; it's a bad idea in the first place, but I was also running into too many infinite recursion errors.

Bug in panels_display_edit()* fixed: comma-delimited imploded pane pid arrays were coming through to the submit handler with extra commas and causing E_STRICT warnings; source of the problem was storing them  a 'hidden' FAPI field instead of a 'value' field; evidently the former is run through some sort of filter (why? it's HIDDEN!). Remainder is mostly doxy updates, plus a few notes about deprecated functions to be removed.

Changes to new show/hide pane buttons to accomodate using two images instead of one; also chose a clear way of handling the nomenclature. Remainder of changes are small doxy updates.

BIG CAHUNA: scrapped functions from split add/edit pane config workflow in the switch over to a unified approach. Added some more default values to content_type array definitions to ease E_STRICT warnings and facilitate other parts of the process.

Reworked panels_plugin_get_function() so that a) it accepts arrays as well as objects containing ct config information (they're usually in array form, anyway), b) uses a var name for the content_type object that's more explicit than '$object', and c) added an isset() check prior to function_exists() to avoid E_STRICT warnings.

Variable naming changes and a few doxy updates for panels_allowed_layouts, per the discussion in #259701