Reflect on char as u32, not uint (which may be u64).

Fixes mozilla/rust#4473.
Add a test for vec::retain
Use vec::truncate for vec::retain
Add Kyeongwoon Lee to AUTHORS
Merge pull request #4477 from jld/char-repr

Reflect on char as u32, not uint (which may be u64).
allowing the entry point name to be something other than main
add build tests
Merge pull request #4484 from sanxiyn/test-retain

Add a test for vec::retain
Add Seo Sanghyeon to AUTHORS
Merge pull request #4485 from sanxiyn/use-truncate

Use vec::truncate for vec::retain
removed self-import (minor cleanup)
s/moved variable/moved value/
finish cleanup