Added $conf['devel_themer_no_whitespace'] variable to give people options of outputting span wrappers without whitespace, in case they are working with themes where the whitespace is a problem: [#297836]

Some cleanup and @todo insertion for devel_themer_toggle(). I need to put some thought into how to disable/enable properly.

Separated permission so users without 'access devel information' can be given access to just the theme development information. [#519054]

Fixed [#534026] by making  devel_themer_catch_function() more robust in its discovery of which theme hook got called.