- restore some CKGlobals behavior because it will cause runtime exception.
- move some classes from CmdHelper to UnvirtContext to make CmdHelper more common to use.
- output warning string when fail to get utf8 or ordinary string.
- add documentation for CKGlobals, VxMath (partly)
- Fix build issue in CKDefines, CKGlobals, VxMath.
- Bring libcmo exception in CKGlobals and VxMath for some illegal input.