#2563 build: Add a experimental directory for new code

[Anders Widell]

Add a new "experimental" directory where new code under development can be added, before it has reached product quality. Also add a new build system configuration option --enable-experimental that will build things under this directory.

[Anders Widell]

commit 254f6a9081607d6c8a7412ebdfd11ede090637ae (HEAD -> develop, origin/develop)
Author: Anders Widell an..@..com
Date: Tue Aug 29 15:45:36 2017 +0200

build: Add an experimental directory for new code and features [#2563]

Add an experimental directory where we can put code for testing purposes, even
though it is not yet ready to be used in production enviromnets. The
experimental code is not built by default, and must be enabled by specifying the
--enable-experimental option to the configure script.