The Model was getting unmaintanable mess. This is an attempt to refactor/rewrite the Model so that data of certain type is exposed in standardized way, offering certain standard manipulations for that data type, and on the GUI side, certain standard widgets to tied to that data.
This rewrite closes#72, #106 and #120.
ConstructPatterns was never used except during compilation, so it
makes sense to have it closer where it is used. We could consider
making it even private function, as the pattern table construction
is quite specific to how compiler compiles and probably not that
reusable elsewhere.
