Thunderbird:UI Reduction

There's too much of it. It needs consolidation and simplification. It also needs reorganization.

Note: Bug 284144 (tracking bug for the preferences rewrite) has been fixed. So, some of the points below may not apply anymore. Please, fix them accordingly.

For example, the Options Dialogue is poorly organized right now.

• The Options Dialogue is accessed by the Preferences menuitem (this is inconsistent, is there a bug on it?).
  In Windows, this is under  Tools | Options —it was changed back to Preferences under Linux deliberately, so that TB would match FF: bug 264061
• Some of the options are used by very few users and should be ditched in favour of system default.
  Provide specifics, please. I'll bet folding money that every one you want to take away has far more proponents than you imagine.
• The junk mail dialogue should be merged into options and grouped along with sanitization options, password options, certificates etc. under Junk Mail and Privacy (bug 257990).
• Fonts and Display should be merged under Mail Display.
• Return Receipts Options should be placed under Composition and Connection Settings should be placed under General (just like firefox).

The Account Settings also needs a redesign.

• We should design something similar to firefox's Bookmark Manager with account grouped by their types (Email, Newsgroup and RSS) on the left pane and the specific settings on the right pane. By default, we will only have one pane What does this mean? with server settings, logins settings, folder settings (user local folder or individual folder), certificate settings and composition settings (html or plain text)
  Composition Settings and Folder Settings are actually per-identity, rather than per-account. The big failing of this dialog is that it doesn't make this clear at the account level.
• Moving the Account Settings into the Options dialogue is being investigated in bug 286664.

There is some ongoing discussion on restructuring the menus.