From Stephan Huber, added support for compile source code of lua with the lua plugin
Added test code for nesting a <hull> within a volume tag.
Added lua-5.2.3 as source code so it can be optinally built as part of the lua plugin, making it possible to work out of the box across all platforms with needing lua as an external dependency.

Added the Cmake option OSG_USE_LOCAL_LUA_SOURCE to control whether to build and use the Lua source code in the lua plugin, or look for lua as an external dependency.
Improved the white space trimming
Added support for a <hull> tag that can be used within <volume> tag.
Tweaked the detection of when the position transform for the hull is required.