[tcltk-perl] changes to Tcl and Tcl::Tk

[Jeff H. <je...@Ac...>]

I implemented the changes to Tcl so that Tcl::icall now uses
Tcl's unknown (AUTOLOAD) mechanism properly and kept the old
version as Tcl::invoke (not directly used anywhere).

I changed Tcl::Tk to not require the extra command stuff for
need_tk in all cases and things still work.

Seeing how small need_tk has become, I think it might be better
to move this to the Tcl module as Tcl::pkg_require, and
possibly take the optional args that Tcl's package require
command allows (version and 'exact' boolean).

Jeff