Update source code references to add git and re-wrap
Update plugins section of manual

• Merge extra plugins section, since they're all provided now.
• Synchronize list of plugins with website list.
• Add new “Obsolete plugins” section for the ones we're not
  shipping anymore for a variety of reasons.
Fix typo
Fix diff format detection.

When '-p' option is used ' @@' can be followed by function name.
Add coloring of diff patches inside emails.
Split 'Get mail' from autoreceive

Currently autoreceive peridically executes 'Get mail',
this change allows user to select separately which
accounts should be fetched on autocheck and which
when user execures 'Get mail' action.