All of the following commands:
notmuch dump
notmuch reply
notmuch restore
notmuch search
notmuch show
notmuch tag
were calling notmuch_database_open with an argument of NULL. This was
a legitimate call until the recent addition of configuration, after
which it is expected that all commands will lookup the correct path in
the configuration file. So fix all these commands to do that.
Also, while touching all of these commands, we fix them to use the
talloc context that is passed in rather than creating a local talloc
context. We also switch from using goto for return values, to doing
direct returns as soon as an error is detected, (which can be leak
free thanks to talloc).
Now that the client sources are alone here in their own directory,
(with all the library sources down inside the lib directory), we can
break the client up into multiple files without mixing the files up.
The hope is that these smaller files will be easier to manage and
maintain.
