Ideal for servers in contained environments where writing to $HOME would
not be not considered polite.

With readline's C-., it's convenient to have the name of the new target
be always the last argument.

New syntax follows this convention and still makes the TEMPLATE optional
by using the plus sign as template name decorator.

The effect of the plus-sign use means that having some template names
already starting with plus would bring silly syntax with double-plus
sign.  Having two types of templates is not really all that meaningful
so let's solve that by merely removing `+` from the names and using it
merely in its decorator sense.

The original regexes would match inside other arguments;

Eg.

    mkexec foo-foo

would match as if -f was presented.

Makes it easier to see explicitly how date is obtained.

As a bous, it will be also easier to parametrize limits.