Oil Generation disobeys chunk borders causing chunk loading during worldgen

[Cydhra]

During world generation forge outputs warnings that are (probably) caused by oil generation:

[15:25:26] [Server thread/WARN] [FML]: Technocracy Foundation loaded a new chunk [-14, 24] in dimension 0 (overworld) while populating chunk [-15, 24], causing cascading worldgen lag.
[15:25:26] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config.

This is (again: probably) because the oil generation disobeys chunk borders and spans multiple chunks instead of waiting for the next chunk to generate.

This could (probably) be fixed like this:

When generating oil lakes for a chunk, ask the random number generator for all lakes in the eight neighbor chunks as well. Then, check whether those overlap with the current chunk and generate only the overlapping parts. Lakes that are centered in the current chunks shall never generate the parts that overlap into neighboring chunks. This way, a chunk may generate only partial lakes, but as soon as the next chunk is generated, the other part is filled as well.