Minor changes
Renamed: some classes from the GDI unit and made that API more compatible with the GDI Support in later versions of Delphi.
    In later versions of Delphi, use those definitions for GDI+ support instead of the ones originally provided.
Some improvement with <button> tag.  This is still not finished and <button> still does not yet work properly.  That may require some changes internally.

Conflicts:
	source/ReadHTML.pas
Fix for issue: 285: Border of <hr>s always visible

Conflicts:
	source/HTMLSubs.pas
Forgot part of a patch.  OOPS!!!
Fixed: Cannot compile GPIPL2A.pas without conditional symbol HasGDIPlus
Revised: GPIPL2A.pas. Reduce number of differences between with or without HasGDIPlus.

Conflicts:
	source/HTMLSubs.pas
	source/MetaFilePrinter.pas
Fixed: dot try to load an iframe without a source.
Removed: TCellBasic.OwnersTag:ThtString using OwnerBlock.Symbol:TElemSymb instead.