Promoted asGetTypeTraits<T>() from the helper add-on to an official interface function

git-svn-id: http://svn.code.sf.net/p/angelscript/code/trunk/sdk@1970 404ce1b2-830e-0410-a2e2-b09542c77caf
Replaced the helper function PrintException with GetExceptionInfo that returns the information in a string

git-svn-id: http://svn.code.sf.net/p/angelscript/code/trunk/sdk@1971 404ce1b2-830e-0410-a2e2-b09542c77caf