Merge pull request #25 from csherratt/Items

Fix build break
Impl appropriate operators for implementors of Zero and One
Reduce code duplication

We can now have multiple definitions in macros!
Merge pull request #27 from bjz/build-fixes

Build fixes
cargo-lite
Call rustc directly in .travis.yml
Remove unnecessary parentheses
Merge pull request #29 from bjz/travis

Call rustc directly in .travis.yml
Merge pull request #28 from cmr/master

cargo-lite
Added scale and translate