gmod_src: Added HTML:HTMLBack()

Revision 588
Added HTML:HTMLBack()
Added HTML:HTMLForward()Changed Files:
[ul]
[li]trunk/src_garrysmod/garrysmod/Objects/cl_lua_panel.cpp[/li][li]trunk/src_garrysmod/garrysmod/gmod_version.h[/li][li]trunk/src_garrysmod/vgui2/vgui_controls/HTML.cpp[/li][/ul]
Committed By Garry Newman