Revise the list of features

Algebraic data types and pattern matching go hand-in-hand. The latter term
emphasizes the advantages, as opposed to the different-ness, and is more likely
to connect with our audience.

Closures aren't a big deal, even Java has them now :)

Move semantics + guaranteed memory safety together give a strong indication of
"modern C++, but better".

Generics are a big deal coming from C++, and they're also a big deal for anyone
comparing Rust to Go (I wish they wouldn't! but it happens anyway)

Also, the new text fits in one line per bullet, on my screen.
Merge pull request #70 from kmcallister/laundry-list

Revise the list of features