Load org support by default, unless mu4e-org-support is set to nil.
Turn off speedbar support by default (set mu4e-speedbar-support to t to
re-enable it).
Move the non-obsolete org stuff to mu4e-org. Rename some things from
org-mu4e to mu4e-org.
Remove org-old-mu4e.el
Define mu4e-context - a structure with settings and enter/leave
functions for contexts, and some functions for switching between
contexts and auto-detecting them.
`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.