a few minor tweaks

Hi Gustavo,

I took a read through the code and added a few comments along the way.

There are still some things I don't understand, mostly the GitHub stuff in `hackedRefs` and what the `git-upload-pack` SubPath is about.

Nathan.
Why does it have to be defined in one line?
```
// Contains returns whether version v contains version other.
// Version v is defined to contain version other when they both have the same Major version
// and v.Minor and v.Patch are either undefined or are equal to other's.
//
// For example, Version{1, 1, -1} contains both Version{1, 1, -1} and Version{1, 1, 2},
// but not Version{1, -1, -1} or Version{1, 2, -1}.
//
```