working on before and after tags
Now allows FSTNode relative placement for XMLNodes:
fh:before
fh:after

Need add XML Attribute android:id to indicate what node do you want to
be before/after.

Currently only working for NonTerminals, will work on Terminals next
Improved so that, if an node id is not present, or if the parent node
does not exist, the fh.before/fh.after then refers to is it prepended or
appended to the list.