Merge remote-tracking branch 'upstream/master' into zoltan-dev
plain staff test to test no connector on a single staff
redefine section plane: a plain mei can contain multiple alternative versions.
fixed: problem when trying to replace an app that isn't in the sectionview_score
meilib.js: define how to remove items from the section plane.
When an item is removed it si replaced with the one that included by initSecionPlane;
Merge remote-tracking branch 'aerhard/master' into zoltan-dev

Conflicts:
	src/meilib.js
Merge remote-tracking branch 'upstream/master' into zoltan-dev
added longa support; fix in documentation
moved getNext and getNextElement to m2v.Util
renamed the breve abbreviation in tables/overrides
added documentation
fixed: default reading/choice don't get inserted to initial plain mei
added test for no margin layouts;

fixed some wrong indentation
added function to get area of all rendered measure staves
moved system and measure logic to separate files
extended measure width calculation
measure w calculation: take voices into account
added auto measure width test
clean-up, added rpt padding rule to measureW calc.
fixed leaks to global object