added addMorphologyLayer()
addMorphologyLayer(), addLemmaAnnotation() and addPosAnnotation() now label
the Alternatives with distinctive names. (alt-mor, alt-lem, alt-pos)


git-svn-id: https://ilk.uvt.nl/svn/sources/libfolia/trunk@17810 12f355fe-0486-481a-ad91-c297ab22b4e3