Don't send inbound session to self and claim and send all keys at once.

While it does improve performance a bit, it is simply bad for most
distributions, since they don't know and probably don't want to
recompile Nheko. So default it to off. Anyone who wants it can still
toggle it on and it is almost no maintenance cost.

Official download links seem to break frequently because of data caps.

May fix #213

fixes #97
fixes #51