fix ThreadTree
Merge branch '0.3.3-feature-urwidtrees' of github.com:pazz/alot into 0.3.3-feature-urwidtrees
complete ThreadTree
clean up threadbuffer
move ThreadTree to widgets.thread
use NestedTree
Thread and MessageTree
update MessageTree -- include body
use ColapsibleTree for message folding
style arrows
respect different thread summary attribute for odd/even lines