Update README.md

List ccache as required in INSTALLING

Should fix #22.

Many args ir fix

This shows up for both pull requests and creating new issues; make this more clear that the CLA only applies to pull requests if you come from the issue page.

It looks like the culprit is IRBuilder<>

separate the irgenerator into another file; unfortunately it doesn't seem to improve compilation times at all

Update README.md

return statement added to python example.