Add multiple mutex groups

[ibboard]

The current design is for singular mutex groups, which limits the various combinations that you can constrain. If the API allowed multiple mutex groups then restrictions like "comes with sword, can replace with axe or broadsword, can add shield, but not if broadsword was taken" can be enforced through mutual exclusion.

[ibboard]

(In r288) Re #180: Add multiple mutex groups

• Add multiple mutex groups to UnitEquipmentItem
• Add new attribute to Race schema
• Make everywhere handle multiple groups instead of assuming one
• Make factory load new attribute then fall back to old (deprecated) attribute
• Add method to Unit to get the blocking items (useful for future UI work to say "replace X and Y with Z")
• Add IsMutuallyExclusive method to UnitEquipmentItem to determine whether mutex groups overlap

[ibboard]

(In r289) Re #180: Add multiple mutex groups

• Make WinForms UI handle multiple groups instead of assuming one

[ibboard]

(In r290) Re #180: Add multiple mutex groups

• Make WinForms UI handle multiple groups instead of assuming one

[ibboard]

Changes in r288 should cover everything. Remaining code is just more intelligent handling in UIs (e.g. in the example in the description the UI should check and say "broadsword is also exclusive of shield as well as sword - remove shield as well?")

[ibboard]

Mark released changes as released

[ibboard]

Mark released fixes as released using radio values

[ibboard]

Mark fix as released under a previous version