Parallel accretion

[MOARdV]

The original Accrete implementation injects a protoplanet into the stellar disk, and it repeatedly accumulates mass either there is no more dust to sweep, or the amount swept is less than 0.1% of the previous iterative step. This means the first seeds are most likely to consume dust, and later seeds scavenge for remains, are absorbed by the earlier protoplanets, or are discarded.

Instead, let's generate a bunch of seeds up front, and let each one iterate over the available dust. Once they've all had a chance, iterate again. Repeat until we've run out of dust.

[MOARdV]

The naïve implementation doesn't work with the darn. It stops accumulating dust, but there's a lot still left out there. Looks like I need to do some more design work.

[MOARdV]

The issue is managing the dust availability. If I update the dust lanes after each protoplanet's iteration, they tend to sweep their lane within 2 iterations. If I don't sweep after each protoplanet and each iteration, then it's possible for multiple protoplanets to sweep the same dust. It looks like I'll need to come up with a different way to manage the dust for this to work.