Log Message:
wxGTK30: update to 3.0.3.1

This is almost exactly the same as the last release but includes
the missing wxPropertySheetDialog::SetInnerSize() method which was
mistakenly removed from 3.0.3.

Please notice that this method is undocumented and not supposed to
be used from outside the library and it is declared as inline and
thus is not part of the library ABI, so its absence in 3.0.3 normally
shouldn't affect the library users, so there is no need to update
unless, for some reason, you need to recompile existing code using
this method with the latest sources, as is the case when building
wxPerl, for example.