WIP: bob in Rust.
Rust: add example implementation for bob
Improve implementation of is_yelling

Thanks to feedback on irc://irc.mozilla.org/rust from sanxiyn and
SimonSapin (as well as others)
Fix whitespace nitpick.
Rust: Move bob files into bob directory
Rust: Bob: Re-add unit test skips

I accidentally removed them in #367.
Add RNA transcription assignment in Rust
Tweak Bob response for consistency. Fixes #622.
rust rna-transcription - rust 0.8 no longer has map_chars, use replace instead
rust - word-count exercise
rust anagram
rust beer-song
rust point-mutations
rust - use named lifetimes in anagrams implementation (thanks @huonw)
rust - clean up beer-song
rust: replace usage of #[should_fail] with #[ignore]
rust - refactor word_count tests
rust - add whitespace to beer-song to ensure logic is in the first 80 cols and strings wrap before 100
rust - add comments to explain why word-count_test looks the way it does
rust nucleotide-count