list optional action fall through ETYPECASE expression

A DEFVAR form was not being evaluated soon enough
to propagate the special declaration of its var
to subsequent uses in the expansion.  Change PROGN
to LOCALLY (DECLARE (SPECIAL ...)) ... to get
that information to the uses.

Command line executables defined with the `define-command' macro now
leverage the `command-line-arity' errors to implement their printing
of help information on arity errors.  This improves over the previous
logic to print help on arity error which did the arity counting of
positional arguments before options were removed from the command line
argument list.

This change only affects clients of the `define-command' macro and the
change should only fix a bug in the previous implementation.

A newly defined and exported `command-line-arity' error will be raised
on arity mismatch instead of a simple error.  This should not affect
any existing clients but it does allow for the targeted capture and
handling of these errors by client applications.

Define-command macro, and misc improvements

Since f2063068 actions will modify the values of the corresponding
argument.  Specifically the value of the argument is set to the return
value of the defined action.  This is a BACKWARD INCOMPATIBLE change
requiring the bump in major version number.

This commit also updates the maintainer listed in the ASDF file.

Allow a command line action to modify the corresponding parameter;
if the modification is not performed, the host program may fail when
executed via the `program-name` function but not via the
`run-program-name` function.

The `define-command` macro now appends a section to the docstring of
the generated `defun` which lists all keyword arguments and their
:documentation descriptions.

This adds a `docstring` argument to `show-option-help` which is used
to generate this list in a format more suitable for a docstring.

This makes it possible to run and test the show-help-FOO function from
the REPL without quitting your lisp session.

The :initial-value field of the command line option specification is
now pulled in as default value to the related keyword argument.

All actions are now called implicitly at the top of the function.

Jason Ruchti authored Feb 12, 2018 and Eric Schulte committed May 22, 2018

Ensure we are in the correct package before execution begins.
This behavior is present in the previous iteration of
`define-command' in bug-injector:src/bi.lisp#650 at rev. 22fd9c79.

Fixes BugInjector regression tests.

Documentation in the README.md and `define-command` docstring.

BACKWARD-INCOMPATIBLE change.  This change will break existing code
which depends on options with actions being dropped from
`*command-line-arguments*`.

Previously if an action was specified then the related option was
dropped from `*command-line-arguments*` causing any reference to it
from the main function to return nil.

With this change the return value of the function invoked by action is
now added to `*command-line-arguments*` and subsequently passed
through to the main function.

Revise some documentation in parse.lisp.

Add support for properly aligning options with and without short and long names in show-option-help.

Instead of having

-f --foo
--bar

Now we have

-f --foo
   --bar

when bar specifies #\Space as the short option designator.

New lines are still supported. Set *print-right-margin* to control where
word wrapping occurs. To provide a sensible default it cannot be smaller than 100.
Update test case.

so cl-launch can compiled in parallel without declaring a dependency.

Format multiline documentation properly indented,
that is each line should start at the same column.
Print option type too and use little bit wider tabs.