Rescaled combat stats

Several combat stats in ToME are rescaled to produce dimishing returns. The rescaling system uses 5 tiers, with increasing costs. A raw input value is converted to a final (effective) value according to the following system:

Tier 1 || 0 to 20 || 1 Tier 2 || 21 to 40 || 2 Tier 3 || 41 to 60 || 3 Tier 4 || 61 to 80 || 4 Tier 5 || 81+ || 5

Tier	Final Values	Cost per point

Examples:

17 || 17 || 1 50 || 35 || 2 71 || 43.66 || 3

Raw Input	Final Value	Tier

Accuracy, Defense, Physical Power, Spellpower, Mindpower, Physical Save, Spell Save and Mental Save are all rescaled this way.