Also includes a refactoring of the List: all methods that accepted
or returned a [from, to] range now return a Range, which is
non-inclusive i.e. [start,end).
Also the assignUnitIds was slightly refactored & a new function
called assignUnitIdsForPatch was added, to assign all unit IDs for
an patch at once.
Closes#157, #163.
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.
