Merged patch with partial implementation to support 16byte aligned native types, e.g. __m128.
The implementation will be turned off by default until it is completed. Turn it on by defining WIP_16BYTE_ALIGN.

git-svn-id: http://svn.code.sf.net/p/angelscript/code@1988 404ce1b2-830e-0410-a2e2-b09542c77caf