Prepare 0.4.3 release

Merge pull request rust-random#584 from dhardy/0.5

Prepare 0.5.5 release

Merge pull request rust-random#546 from dhardy/0.5

Prepare 0.5.4 release

Merge pull request rust-random#530 from worr/bug/openbsd-typo-5

Rename `s` -> `dest` on OpenBSD and bitrig

Update version and changelog for 0.5.2 release.

Merge pull request rust-random#498 from dhardy/0.5

Update changelog and version number for 0.5.1 release.

Merge pull request rust-random#498 from dhardy/0.5

Update changelog and version number for 0.5.1 release.

Merge pull request rust-random#469 from pitdicker/rand_05_release

Update version numbers: rand_core 0.2.0 and rand 0.5.0

Merge pull request rust-random#469 from pitdicker/rand_05_release

Update version numbers: rand_core 0.2.0 and rand 0.5.0

Update version numbers: 0.2.0-pre.0 and 0.5.0-pre.2 releases