Make it possible to use a "conflated grammar"

[heatherleaf]

The new tool gf-conflate-params can merge parameters to make a grammar accept errors: https://github.com/MUSTE-Project/gf-canonical-transforms

To be able to use this in MULLE we need to do the following:

• be able to specify separate PGFs for the source and target grammars (one of them is the "conflated" grammar)

• compare trees from different PGFs: simplest solution is to remove all __xxx suffixes of function names in the tree, and then compare them. This means changes in:

  • the muste lib: Muste/State.hs (and probably in muste-ajax)
  • and the javascript: the function matchy_magic in app.js