cherry-picking from other forks

[MLopez-Ibanez]

Some people are still fixing stuff in their forks of poliastro, as one can see in the Network display:

https://github.com/poliastro/poliastro/network

I think it may be worth it to contact those people whose fixes you may want to incorporate. This may bring you additional contributors and spread the word that hapsira is the continuation of poliastro.

[s-m-e]

Indeed - got swamped due to moving. Will resume here shortly.