Adds Roll D100 To GM Screen

Also changes formatting a little for consistency
Minor GM Screen Formatting Fixes
Introduces an Equipted Item Set Concept to Inventory
Adds Button to Equip Visible ItemSet to UI
Fixes binding to agility and tmr

Makes Agility and TMR have a backing field in the VM so it is possible
to refresh these properties.
Not sure what the real pattern we want to go for is. Made some TODOs so
we think about this before we keep copying it.
Fixed UI bug in GM Screen Dice Roller