Fix mine rate half life calculation.
Increase RGS range from 500 to 800.
Don't show alien mine rate to human builder.
Always send correct mining efficiencies to clients.

The previous approach would sometimes send incorrect values after a RGS got built or destroyed.
The content of the config strings was also misleading as they contained 2x the real efficiency.
Cleanup G_CalculateBuildPoints.

Merge conditional statements with same body. Move sanity checks (BP >= 0) to the end.
Merge pull request #205 from Viech/resources

Mine rate related fixes and improvments.