Estimator for OctoPrint that uses data embedded in gcode by gcodestat

Requirement

Needs octoprint 1.3.9 that implements
- http://docs.octoprint.org/en/maintenance/plugins/hooks.html#octoprint-filemanager-analysis-factory
- http://docs.octoprint.org/en/maintenance/plugins/hooks.html#octoprint-printer-estimation-factory
Needs M117 codes in your G-Code to look like (if you do not change --m117_format option in gcodestat default output will work perfectly):
- M117 100% Remaining 1 weeks 6 days ( 07:54:19 )
- M117 100% Remaining 4 days ( 02:04:19 )
- M117 35% Remaining ( 12:43:04 )
- M117 17% Remaining ( 43:04 )
- M117 5% Remaining ( 04 )
You can use gcodestat to pre-process your G-Code files and embed these M117 codes

Auto preprocess the G-Code file on upload and embed M117 codes (use externally gcodestat for e.g. for speed)
Push a % value to the OctoPrint (I have the value I just have no clue how to send it to OctoPrint)
Add configuration so that custom regex can be used to parse M117 valuess
Python3 + test with latest octoprint

I'm no Python developer, I do C++, so if you can suggest code cleanup, solving something differently etc. feel free to step in, this code would never be presented without serious help from foosel!!!
In case there are no M117 codes that can be recognised the original estimator from OctoPrint will be used
In case SDCARD print is used the original estimator from OctoPrint will be used

I got pulled into some %$@#)%^ so no time to work on this now, I hope I'll be back in few weeks