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.

Overview of changes:

 *  Simplified configuration

The host split turned to be a vast overengineering.

Overview of changes:

 *  Fixed initial errors caused bu migration from mydots
 *  Fixed packaging

We don't run .lua scripts directly; we use imapfilter which solves its
own dependencies (uses liblua5).

Overview of changes:

 *  Added everything