Provide full Tcl patchlevel to tcl.pc and move private libs to "Libs.private".
Provide full Tcl patchlevel to tcl.pc and move private libs to "Libs.private". 
Record the fact that Tcl 8.6 requires Zlib 1.2.3 as a minimum. 
Supply both the shared library and the stub library to "Libs": Only one of them will actually be linked in, depending on whether -DUSE_TCL_STUBS is defined or not.
Fix bug [e663138a06]: Test failures in "string is"
[792641f95b]: Normalized win32 paths should never contain backslash.
[792641f95b]: Normalized win32 paths should never contain backslash.
Fix [3118489] for Windows only: NUL in filenames. This allows various characters to be used in win32 filenames which are normally invalid, as described here: [http://cygwin.com/cygwin-ug-net/using-specialnames.html#pathnames-specialchars]. The Cygwin shell can handle those same filenames as well. In other shells (cmd.exe/mSys) or on the Windows desktop the filenames will look strange, but that's all.
Fix [3118489]: NUL in filenames, now fixed for both Windows and UNIX. 
For consistancy, any NUL character in a filename prevents the native filesystem to generate a native file representation for it. Other filesystems than the native one may still accept it, but it's not recommended.
[e663138a06] Fix the new INST_NUM_TYPE instruction so that the boundary
cases of [string is] on integral values are computed right.  Code is now
correct, though still suffers from a large amount of ugly.
Test-cases which pick up the completion of bug-fix [e663138a06d98e48b5fbb42cc015cf1698f486cd|e663138a06]. Thanks, Don!
merge trunk