Enforce `top` and `bottom`

This version now enforces top and bottom, clamping operations that would otherwise overflow the bounds of an Int53 (see #8, thanks @hdgarrood)

It also implements degree in a way appropriate for integers (see #7, thanks @clayrat and @garyb).

The dependencies have also been updated for Purescript 0.10.5 and purescript-prelude 2.3.