Change the names of all methods in the Wm class: they are now

Change the names of all methods in the Wm class: they are now
wm_title(), etc.  The old names (title() etc.) are still defined as
aliases.

This brings all methods up to use the same naming convention: whether
the Tcl syntax is

   .window.path.name command subcommand [options]

or

   command subcommand .window.path.name [optins]

the Python equivalent is always

   windowobject.command_subcommand(options)