Add Guideline Generation to MEIGarage

[anneferger]

• Conversion of generated ODDs to Guidelines
  • add option to Customize
  • add extra Converter for external files as well
• See special workflows in https://github.com/music-encoding/music-encoding/blob/develop/build.xml and https://github.com/music-encoding/guidelines

[riedde]

The workflow in the music-encoding build.xml is able to build a compiled-odd and the HTML version of the guidelines. There is also a workflow for generating a PDF with prince-XML, but I haven't found the place it is stored. Maybe @kepper knows a quick link :)