fix #565 - select sender by correctly parsing recipients
Merge branch '0.3.4-fix-recipients-565'
docs: for Envelope
fix Envelope __[sg]etitem__

to actually work on self.headers as *list* of strings for each key.
this hasn't been a problem since these convenience methods are not
really uset at all atm..
Merge branch '0.3.4-docs-567'
postpone binding if candidates with same prefix exist

This ensures that commandlines that are bound to a key
are not fired right away but wait a little (config option 'input_timeout')
in case there are other bindings with this key as prefix.

This allows to bind for instance 'g g' to move up while at the same time
one can bind 'g' to global replies. Without this change, the 'g' binding
would be fired right away.
merge thread.MoveFocusCommand and global.Movecommand

this removes the thread command 'focus' in favour of a more refined
'move', that, in thread buffers also interprets directions
  'next', 'previous', 'parent', 'first child' and 'last child'.
pimp default bindings
Merge branch '0.3.4-feature-input-prefixes' into 0.3.4-feature-urwidtrees
Merge branch '0.3.4-feature-urwidtrees' of github.com:pazz/alot into 0.3.4-feature-urwidtrees
reorder default bindings for toggle[headers|source]
re-implement toggle-all-headers
re-implement toggle-source.

this also makes that dource/bodytext content in a messagetree
gets one Text widget *per line* and thus means smoother scrolling w/o
strange jumps.