Oregen correction pass Part 3

This implements modified oregen for specific Eras.

Information, the "Present" Era, and Sandbox oregen are equivalent, and broadly follow the RR2 standards.

Earlier eras, however, have wilder ore distribution. The farther back you go, the more extreme and unfocused the distribution becomes until by the Primordial Era it is completely amorphous.
Additionally, in certain Eras the available ores may shift dramatically to reflect the focuses of that period.