resource placement overhaul (and other improvements)

[azum4roll]

• A separate Impact and Ripple table has been made for each strategic resource (instead of all of them sharing one).
  • The order of placing strategic resources should no longer matter
• Size of coal deposits reduced. Amount of coal deposits increased.
• Resource placement follows Civilopedia
  • Coal: grassland, plains. No longer on tundra.
  • Gold: grassland, plains, desert. No longer on tundra.
  • Silver: tundra, desert. No longer on grassland/plains.
  • Copper: can be on all featureless plots, including snow.
  • Gems: can be in jungle in addition to featureless non-snow plots.
  • Salt: plains, desert, tundra. No longer on grassland.
  • Sugar: flood plains and marsh only. No longer in forest/jungle.
  • Truffles: can be in marsh in addition to forest/jungle.
  • Furs: flat forest tundra only. No longer on plains.
  • Ivory: open flat plains only. Grassland ivory was a bug.
  • Cotton: can be on featureless desert in addition to grassland/plains.
• Clear Marsh moved to Construction (was Iron Working)

For devs:

• Enum tables for region division mode, region types and impact layers have been made for readability.
• Constants NUM_REGION_TYPES and NUM_IMPACT_LAYERS have been added so we don't need to modify so many lines of code every time we add more of those.
• The bulk of GenerateGlobalResourcePlotLists, GenerateLuxuryPlotListsAtCitySite and GenerateLuxuryPlotListsInRegion have been merged into one function GenerateResourcePlotListsFromSpecificPlots since they mostly do the same thing.
• New IsTropical function to check whether a given y coordinate is tropical. It factors in the humidity setting.

Communitu_79a changes:

• Use new impact layers, adjust strategic rate accordingly
• BUGFIX: AdjustTiles now works for Even More Resources