Merge branch 'master' into core-updates

Conflicts:
	gnu/packages/image.scm

gnu: Have lua-5.1 compile a .so

* gnu/packages/patches/lua51-liblua-so.patch: New file
* gnu/packages/lua.scm: Use of lua51-liblua-so.patch in lua-5.1

Signed-off-by: Ludovic Courtès <ludo@gnu.org>