Alternative constructor to attach to a running omxplayer process without loading a source

[maxsatula]

Feature Request

Description

Alternative constructor to attach to a running omxplayer process without loading a source

Example use case

1. I run omxplayer myself, and would like Amazon Alexa (or whoever) to control my player using this module. Hence I would like to have an ability for the module to attach to a dbus address of the already running player process, rather than spawning a new one.
2. Also, I do not want to supply a media source (which is a mandatory argument now) as by the time the module is expected to attach to the player, some media is already being played.

It does not seem to be difficult to implement, maybe I'll submit a pull request some day once I have a chance and inspiration, but if someone gets there faster than me, I would appreciate it.

Thank you!