Fix unit test build
Use macro for generating wrapper impls
Create zip macros for automating repetitive code
Add AUTHORS.txt
Update makefile to look in lmath/extern when compiling
Update README
Use core::num::{Zero, One, NumCast} traits for 'zero', 'one' and 'cast' methods
Remove unnecessary imports
Remove NumCast type parameters

The NumCast type parameter is no longer needed as it is a constraint of numeric::Number
Formatting
Make trait names more succinct