ENH: Split install script into two parts.  Added basic support for adding more files to the distribution and creating packages.

     Both styles are now searched taking advantage of the NAMES option in
     FIND_LIBRARY.

BUG: fix jump to directory and build for nmake if library path is not set. combine OutputBuildExecutableInDir and OutputBuildLibraryInDir into OutputBuildTargetInDir

ENH: change the search path order (if several Tcl/Tk are installed, the "current" version is likely to be the one that is bound to the wish/tclsh found in the PATH)

BUG: Generated vtkCommand prototype cannot be extern "C" because it may not match with the version in VTK.