Use modelix/incremental in MPS-extensions/de.q60.mps.incremental.runtime

[slisson]

The implementation in [1] is basically the first version of [2]. [2] is more scalable. An integration of [2] with MPS will allow to incrementally compute results of ModelQL.

[1] https://github.com/JetBrains/MPS-extensions/tree/master/code/shadowmodels/solutions/de.q60.mps.incremental.runtime
[2] https://github.com/modelix/incremental