Removed flags parameter from GG::StyleFactory::NewTabBar(Left|Right)Button.

git-svn-id: svn://svn.code.sf.net/p/freeorion/code/trunk@7618 dbd5520b-6a0a-0410-a553-f54834df5b05
Removed flags parameter from GG::StyleFactory::NewScroll(Left|Right|Up|Down)Button.

git-svn-id: svn://svn.code.sf.net/p/freeorion/code/trunk@7619 dbd5520b-6a0a-0410-a553-f54834df5b05
Removed flags parameter from GG::StyleFactory::New(H|V)(Scroll|Slider)TabButton.

git-svn-id: svn://svn.code.sf.net/p/freeorion/code/trunk@7620 dbd5520b-6a0a-0410-a553-f54834df5b05
Made GG::Button derive from GG::Control instead of GG::TextControl.

git-svn-id: svn://svn.code.sf.net/p/freeorion/code/trunk@7621 dbd5520b-6a0a-0410-a553-f54834df5b05