Expose inherent methods in lua bindings.
Expose inherent methods in lua bindings.

These methods are defined in parent classes, but aren't exposed in Lua in an
easy to use manner.
This fixes issue #1002

RealityFactory/CEGUI,cbeck88/cegui-mirror,RealityFactory/CEGUI,arkana-fts/cegui,cbeck88/cegui-mirror,arkana-fts/cegui,RealityFactory/CEGUI,cbeck88/cegui-mirror,arkana-fts/cegui,arkana-fts/cegui,RealityFactory/CEGUI,cbeck88/cegui-mirror,RealityFactory/CEGUI,arkana-fts/cegui,cbeck88/cegui-mirror