Make names of Drafts/Sent maildir folders configurable in notmuch config.
Update build instructions for Mercury 13.05.
curs: Add support for default colour -1.

This is an ncurses extension.
Use the terminal's default background colour.
Merge branch 'default-colour' of https://github.com/wangp/bower

Conflicts:
	curs.m
	pager.m