feature/gbuild_components is finished

Hi all,

it would be nice if people tried feature/gbuild_components on their
Windows or MacOS X machines/tinderboxes. It builds and smoketest runs on
Linux and Linux/MinGW, so I do not expect problems, but anyway .-)

The branch converts two modules to gbuild--stoc and io--and, more
importantly, refactors UnoApiTarget. There are two new modules: UnoApi
and InternalUnoApi. UnoApi replaces the current UnoApiTarget in
functionality (and even simplifies its use a bit, because headers are
created and delivered automatically without any need to ask for it).
InternalUnoApi is intended for internal (surprise :-) use, e.g., rdbs
created from XML description (like in stoc and io) or module-specific
idl files.

It is now possible to generate more than one "variant" of headers, by
using new functions of gb_LinkTarget: get_internal_api,
get_internal_bootstrap_api and get_internal_comprehensive_api, which
generate the headers by (in the listed order) cppumaker -L (this is also
the default for headers generated by UnoApi), cppumaker and cppumaker -C .
This should cover all the usage in current build system.

If there are no protests, I will merge the branch to master on Thursday
morning.

D.