Define a new `mail-user-agent' (`notmuch-user-agent') and use it by
default. Re-arrange various routines that send mail to use this
(compose, reply, forward). Insert a `User-Agent:' header by default.
This is the real commit for this functionality this time. The
previous attempt to merge this code:
commit 57926bc7b0
was botched (by Carl Worth, not David) to include only the Makefile
change. So the build was broken until this commit that actually adds
the new file.
Fix missing argumen in declaration of notmuch-search function and add
a definition of notmuch-search-continuation to avoid warning about
assignment to a free variable.
This is based on the prototype that Carl Worth described in the TODO
file. It provides a search bar as well as support for recent searches,
saved searches, and a list of all tags in the database (as well as the
number of messages with each tag).
