Human-readable hat ids

Hat ids are uint256 bitmaps that use the following structure to achieve an "address" for each hat that includes information about the tree of admins for the hat:
- The first 4 bytes are reserved for top hat id (we can think of this as the "domain" of a given hat, often corresponding to the DAO the hat belongs to)
- The remaining 28 bytes each represent a single hat level, fitting 1 admin hat and 255 "child" hats.

Displaying the id as a binary number would require way too much space, but displaying it as a base-10 number occludes the above address semantics. Displaying the id in hex is a good compromise, since it exposes bytes as described above.

But, starting with hex we can make hat ids even more human-readable by...
1. inserting dots between hat levels
2. trimming trailing hat levels (trailing empty bytes)

The result would look something like this:
For hat id `0x0000000101010000000000000000000000000000000000000000000000` -- which is the first hat at the second hat level, whose admin is the first hat at the first hat level, whose admin is the first top hat -- the human-readable id would be...

`00000001.01.01` or perhaps even `1.01.01`