Replace HTTP links with HTTPS

[GabrielMajeri]

This pull request replaces http:// links with https:// links, where possible.

Fixes #166.

[dhardy]

Needs update, preferably after #209 is merged.

[pitdicker]

@GabrielMajeri Are you willing to rebase this, or shall I do so?

[GabrielMajeri]

@pitdicker Done, fixed more links and removed some trailing whitespace.

[dhardy]

What are all the whitespace changes for? I like having aligned empty lines. Never mind, I'll merge once CI is happy.

[GabrielMajeri]

@dhardy rustfmt is the one that suggested trimming the whitespace.

[pitdicker]

Wow, quick work!

Eventually I think it would be nice to run rustfmt and clippy on rand, but that should probably wait until the changes from @dhardy's branch and the open PR's are merged.

[dhardy]

If you like, just don't hold them up as gold standards. I've disagreed with rustfmt a few times before (including one case where it caused a compile error); Clippy has some great suggestions but also a few that are completely pointless.