salbool: a rewriting plugin that flags most uses of sal_Bool

...that would not lead to silent changes of the code.  That is, it does not warn
about sal_Bool parameters of virtual functions, so that (not yet rewritten)
overrides do not silently become overloads instead.

The plugin is in store/ for now, because not all of the code has been cleaned up
yet.

Change-Id: I6e9b3847eb26c3090f375045188d38097052defe