Fix numerous style and correctness issues.

1) Comparison between signed and unsigned types.
2) Use of right-binding const
3) Line length > 80 chars
4) No whitespace between identifier and parens
Fix warning triggered by gtest-tap-listener.

A function had a const void return type, this is a no-op and triggers
compiler warnings.
Switch to using common-universal-cmake.

This means we're able to delete direct usage of a number of CMake
related submodules and let common-universal-cmake handle that for
us. It also means that we can cut down on boilerplate substantially,
for instance most things could be moved over to
polysquare_add_library.
Merge pull request #62 from smspillaz/yiqi.item_53

Switch to using common-universal-cmake.