[CMake] Maintainer for FindX11, FindOpenGL, and FindTCL (and friends)

[Clifford Yapp]

Looking at http://www.cmake.org/Wiki/CMake:Module_Maintainers (thanks
Brad for the link) it looks like my best option may be to actually
volunteer for the maintainership of FindX11, FindOpenGL and
FindTCL(sh/stubs/etc...), as they are not listed as being actively
maintained.

Since I need these modules in any case and would have to keep them
working for my own purposes, this would seem to be a workable
solution.  I had hesitated to propose this step because I had figured
Kitware would prefer to itself maintain the Find modules for such
central functionality, but if they are indeed on the list of modules
for whom a maintainer candidate is sought I'm willing to give it a go.

FindX11.cmake and FindOpenGL.cmake are fairly straightforward, but in
the case of Tcl/Tk I would prefer to move back from the splitting up
of Tcl/Tk functionality to just FindTCL.cmake - the primary reason for
this is to avoid situations where there are multiple Tcl/Tk systems
installed and the tclsh search returns a tclsh executable that is not
the tclsh associated with the libraries of the Tcl selected by the
find_library logic.  It might be conceivable to put some constraint
logic in to make a find_package on one to conform to the results
already found by another, but that seems awfully forced.  By the same
token, there is no reason the tclsh and tclstub find files need to
march to the same drummer as the FindTCL.cmake file, although the
results might be somewhat surprising if they didn't.

Tcl/Tk appears to have been a significant focus of the original
developers.  I'm leery about becoming maintainer and making such
radical changes to something the Kitware devs probably need without
approval, so I'd like to discuss it here (unless it's just flat out
unworkable, of course ;-)

Cheers,
CY