fix MEM_DEBUG and leak, ported from mig-strip-brutal
Restrict the stub library to only use Tcl_PkgRequireEx, Tcl_ResetResult	and Tcl_AppendResult, not any other function. 
This puts least restrictions on eventual Tcl 9 stubs re-organization, and it works on the widest range of Tcl versions.
merge trunk
empty merge of trunk (via no280)