Get rid of cu, wrap a few long lines and compactify As_project.

`CU, CU, value cu and type cu type are replaced by `Unit, Unit, value unit and type comp_unit.

Sorry couldn't live with these one-line accessors that each took three lines to define, so I compacted the defs a bit in `As_project`. I work on lapots with limited vertical space and I don't see the point of scrolling that much.