Resource generation by units in cargo

[Captain Kwok]

This is kind of similar to an idea that I sent to Malfador re: facilities in SE5.

I suggested that planets be a random size between x and y 'spaces', rather than a specified size like tiny or medium etc. Facilities would occupy different amounts of space, and so each planet could hold a unique amount of facilities based on which ones were present rather than SE4's 'static' amounts.