clang-importer: fix metadata entry "source_file_line" for Typelib::Type

before, the path to the header-file was stored into "orogen_include",
which is (as far as I see) is used by orogen at a later stage.  now,
"/path/to/file:line:column" is stored into source_file_line", as gccxml
does (gccxml.rb:445).

clang returns line-numbers starting with one, so the gccxml-related
trickery of adding 1 to the line-number is not needed.

renamed function and added comments for more claritry.

wondering: wouldn't it be a sleeker interface if
Typelib::Type::setPathToDefiningHeader() called
Typelib::Type::addMetaData() all by itself?

Signed-off-by: Martin Zenzes <martin.zenzes@dfki.de>
clang-importer: implement "opaque_is_typedef" metadata

was not implemented before. tested with the appropriate test-opaque file
in the "typdefs" testcase.

Signed-off-by: Martin Zenzes <martin.zenzes@dfki.de>
typemodel: make "Type::ValidCategories" be a proper enum-value

and rename it to "NumberOfValidCategories"

"Typelib::Type::ValidCategories" was wrongly set to "Compound+1", a
remnant from 2005 -- impressive by itself ;-) the "Opaque" and
"Container" enums where then added in 2008 without adapting the value of
"ValidCategories". Seems like nobody is using this, so...

not sure: setting the start-value of the enum in "Typelib::Numeric"
to "Typelib::Type::ValidCategories" is nice but futile?

Signed-off-by: Martin Zenzes <martin.zenzes@dfki.de>
opaques: don't set/import/export the size of "Opaques", it is always zero

opaques entries in a tlb have no size. not sure here, if this would
break stuff elsewhere... is this property read anywhere? don't know...
anyways...

Signed-off-by: Martin Zenzes <martin.zenzes@dfki.de>
typelib: fix -Wswitch warnings by throwing in "default" case

(or return "Qnil" for ruby)

after adding a new entry into the type-enum, there popped up some
-Wswitch errors because some "default"s were missing. added some throws.
also removed an assert which nobody can catch at runtime.

removed the "shut up gcc" dummy-return-statement -- does gcc still
complain in 2014?

Signed-off-by: Martin Zenzes <martin.zenzes@dfki.de>