Remove trailing whitespace.
Prefer .. to -> in Java interop.
Prefer condp to cond in certain cases.
Prefer case to cond/condp in certain cases.
Use a set as a predicate when appropriate.
Use inc & dec instead of + & -.
Minor tips.
Merge pull request #15 from ghoseb/master

Add a bunch of tips and some cleanups
Added contribution guidelines.

The contents of CONTRIBUTING.md will be taken into account by GitHub
and a link to them will be displayed to users creating new issues.
Merge branch 'master' into zh_CN

Conflicts:
	README.md