fixed sorting of threads.

If you copy mails to your local maildir their receive date is set to
the time of copying. Ordering by last date received does not make sense in
this case.
added key bindings to mark all mail as read and to tag all duplicates
comments added
improved alias usage
higher contrast for better readability
removed mrtazz custom color settings
questions before editing are helpful
enable spell checking

Spell checking can be done directly in vim by adding this line to ~/.vimrc:

:autocmd FileType mail :nmap <F8> :w<CR>:!aspell -e -c %<CR>:e<CR>
actually these settings fix some key bindings changed by the nntp extension
quote the file name - there may be whitespaces
added more mine-types
these are defaults
more vi!
removed mrtazz filtering macros
removed mrtazz not much integration
bound next-unread-mailbox to µ
removed trailing redundant quotes
these are defaults
set forward_decode="no" breaks weed for inline forwarding
more nice colors