exposed list of Vex.Flow.Stave objects in order to retrieve coordinates
some white spaces
removed mei: prefix from TC.Isaac.xml
reorganised arguments of createSingleVariantPathScore() and MeiLib.parseAPPs()
supporting @clef.visible

added test for tenor clef
correct reference to argument in MeiLib.createSingleVariantPathScore
Merge branch 'master' into variants
removed getElementsByTagNameNS from variants.html

removed first paramter when calling MeiLib.createSingleVariantPathScore
removed incorrect description for MeiLib.parseSourceList()
MeiLib Variant Handling reorganised

Added: MeiLib.VariantMei class
Added: MeiLib.SingleVariantPathScore class
Moved variant parsing methods inside the above classes.
Slicing MEI
fixed a typo