"other" overcast custom value, customizable overcast table per lore (i.e. Dhar)

[silentmark]

This is small request that would allow two things:

• customize overcast tables per lore, i.e. WoM doesn't describe overcast rules for Dhar, this option would allow to define custom table for Dhar spells that would have lower values.
• customize "other" value for overcast rules instead of hardcoded "2". this would allow to customize behavior of some spells from unofficial grimoire, i.e. Ward (+3 SL to increase Ward power) or Terryfing and few others. In addition, this would go beyond, and allow to "define" a formula tha would increase cost of "other" overcast for each step in similar way to table.