Overview of changes:
* Removed restriction to four valid actions
User can now define as many actions as they want by simply adding
handlers for them.
* Improved usage messages
* Added meaningful error messages
* Added arguments to show version
* Added 'last' branch to keep latest version
* Fixed and cleaned up packaging info
* Updated for Shellfu v0.10.*
* Codebase maintenance
Having just 4 valid actions (albeit they do form a meaningful workflow)
was rather historical limitation caused by author's negligence.
User should be able to define any actions they want by simply creating
handlers for them.
Later we might want to provide a guidance (template) for that, but
that's a TODO item.
Fix dependencies, use spaces instead of tabs in .spec file, rename
`imapdomo.spec` to `template.spec`, rename `imapdomo.install` to
`install`, remove unnecessary `override_dh_auto_install`, add URL to
.spec, update Summary, clean up.