* treewide: http -> https sources
This updates the source urls of all top-level packages from http to
https where possible.
* buildtorrent: fix url and tab -> spaces
Many (less easily automatically converted) old-style strings
remain.
Where there was any possible ambiguity about the exact version or
variant intended, nothing was changed. IANAL, nor a search robot.
Use `with stdenv.lib` wherever it makes sense.
