New usage instructions, revised key bindings, get 'savemap' vimscript.
Rework the manual a bit, and remove the key bindings description.

The Vim help file is a better place for them, and they are easier
to maintain if they are in one place only.
Clean up test files a bit.

The test files now have "#!perl" as their shebang line, reminding the
reader that they are perl files, but that they are not meant to be run
as standalone executables.
Implementation of improved key bindings, as documented in VimDebug.txt.

Other improvements were intertwined at the same time, and although I
would have preferred to commit them separately, there it is.

Protocol.pm attributes were prefixed with "k_" (for "constant", let's
say) making them easy to recognize. Also, VimDebug.vim and the *.pm that
need those values now obtain them from Protocol.pm, instead of
hard-coding copies of their values locally.

Debug.pm's read() method got simpler by letting Perl.pm handle both the
parsing and the setting of the debugger status.

I added empty lines between the functions in VimDebug.vim. I found it
just too hard to read the code without them.

A bit of formatting cleanup was also done in the files (remove trailing
blanks, use DistZilla'isms, etc.).
Change 'v' key bindings to 'x', to better align with the perl debugger.
Don't track the Vim help tags file.

We may have built it for testing.
Implement the "step out" feature.
Improve our developer minimal Vim launcher.

It now has an option to launch gvim (-g) instead of vim and one to have
a map already defined on <F12> (-m) before loading VimDebug. It also has
some perldoc now.
Have a gvim menu for VimDebug.

Actually, there are many changes in this commit, and a lot of
refactoring. For example, the port number (6543) is now supplied by the
VimDebug::Daemon->port() method, and the "done file" ('.vdd.done'), by
the VimDebug::Protocol->k_doneFile() method.

But the biggest changes are in the VimDebug.vim file:

User configurable variable definitions are grouped together at the
beginning of the file, and are named like "s:cfg_fooBar". Similarly,
global variables whose values may have been set before loading the
VimDebug module are grouped there also.

There is now a 's:Initialize' function used to, yes, initialize
everything necessary for proper functioning of VimDebug. It is defined
early in the file, and it is called at the end,

There are now Vim commands (as opposed to functions) only to launch the
debugger and to toggle the key bindings (VDstart, VDtoggleKeys).

A good half-dozen functions were added to manage the interface settings
(key bindings, menus).