minor refactoring, add a comment about StackValue instances
minor refactoring, add a comment about StackValue instances

Signed-off-by: Ömer Sinan Ağacan <4a3f4704bc8d2eaf9c65274e8718c7eed4a49074@gmail.com>

osa1/hslua,osa1/hslua,tarleb/hslua