Updated README and ARCHITECTURE docs to reflect current reality. Underline details of l10n_localpacks and complete docs for implemented l10n_client connection

Also includes dingbat font explanation by keith.smith from #203866

 - previously l10n_server and l10n_community were divided with the thinking
   that a different editing interface might be used on the same data
 - but real life discussions showed that a cool interface is supposed
   to be tied to different data sources

So this upgrade separated the data sources (connectors) from the community interface.
Now only the previously implemented l10n_drupalorg connector is here, but it is easy
to implement others, as I'll do later.

There are also some smaller bugs fixed, but otherwise a huge reorganization was enough
for starters. I could not stop myself from cleaning up the suggestions architecture
at the same time though. So now the history and suggestions are not stored separately,
but are accessible from the same table (as inactive records for history values and as
suggestion records for suggestions). Otherwise they use the same data as translations,
so there was no reason to separate that out.

I also fixed smaller import and export issues, so these operations work better.

HTML and form structure cleanup is on the TODO list for the string editing interface,
which will be hopefully followed by a great UI improvement session later.

l10n_server:
 - made it reuse potx, instead of copying it
 - redone the UI to simplify user interations
 - simplified the URL scheme
 - organized functions logically
 - fixed coding style issues, like single qoutes instead of double quotes
l10n_community:
 - completely redone the UI, tabs instead of select boxes and arbitrary forms
 - abstracted common theme functions (copy icon, progress bar) out
 - constants instead of magic numbers
 - predictable help instead of global variable mangling
 - added more documentation
 - ordered the functions logically

Lots more to come. These big changes are not the end.

migrating lt_server and lt_wt to l10n_server and l10n_community, cleaning up README and TODO list, hook ordering and code comments

starting lt_server migration to l10n_server with a HEAD readme to point people to the Drupal 5 branch