Use (preferred) Tcl_ObjSetVar2 in stead of Tcl_SetVar in tclAppInit.c, both UNIX and Win.
Add test-case for Bug #2438181 (which passes in Tcl 8.4 but fails in 8.5/8.6).
Provided by Poor Yorick
Fix bug #2438181: Incorrect error reporting in traces. 
Test-case and fix provided by Poor Yorick.
revert mangling with "code" variable. This caused unrelated var.test failures.
Fix bug #2438181: Incorrect error reporting in traces. 
Test-case and fix provided by Poor Yorick.
Bug 3605401: Compiler error with latest mingw-w64 headers
[Bug 3605401]: Compiler error with latest mingw-w64 headers.
[Bug 3605401]: Compiler error with latest mingw-w64 headers.
merge trunk. 
doc improvements