de-plaintext: Review Versioning chapter
de-plaintext: Add new Frescobaldi screenshot

Reorganized the Frescobaldi screenshot to be better
recognizable in printout:
- increase code text font size
- detach the Quick Insert Tool
- use explicit \score block to be referenced in the text
de-plaintext: Review Lilypond Chapter
de-plaintext: Review LaTeX Chapter
de-plaintext: Review Applications Chapter WIP