* mu4e/Makefile: allow configuring the lispdir

`lispdir` is no longer hardcoded in the Makefile.

Users can set the desired `lispdir` at configure time, with `./configure
--with-lispdir='...'`; or at install time with `make lispdir='...' install`.

The default install path is the folder `mu4e/` inside whatever AM_PATH_LISP
finds, which is probably what the original default intended.

This change fixes #320.
* mu-proc: Don't rename when moving inside a Maildir

`mbsync' expects messages moving inside a Maildir (from `new' to `cur',
for example) to mantain its basename.
Merge pull request #323 from uu1101/configurable-lispdir

* mu4e/Makefile: allow configuring the lispdir
* minor
* merge branch 'master' of github.com:djcb/mu
Merge pull request #322 from uu1101/keep-basename-inside-maildir

* mu-proc: Don't rename when moving inside a Maildir
* mu4e: fix warning
* mu-cmd-server: set default to 500 results (thanks to Frank Terbeck)
* merge branch 'master' of github.com:djcb/mu
* mu4e: add note about Inconsolata to Tips & Trips (thanks to mistrey)