support adjacent multiline lyric blocks (fixes #68 on GitHub)

mxl import dynamics and directions; minor refactor last commit, remov…

…e redundant condition

Regression in v1.811 broke lyrics on long notes. Fixes #77 on GitHub

MusicXML import collapse spurious newlines in XML titles

MusicXML import ignore embedded mimetype

refactor and fix note regex (may help with #76)

more fixes for MusicXML imports with multi-voice per part

support multiline lyric blocks (fixes #68 on GitHub: newline after L:…

… to 2 newlines)

support MuseScore style MusicXML voices within parts (fixes #72 on Gi…

…tHub, some others not fixed yet)

support omitting space between note and slur (fixes #70 on GitHub)