Remove excessive whitespace in map headers.

Use the "map" macro instead of using GROUP_* and MAP_* constants.
Also remove redundant "(bank then label)" comments.
Don't use Olivine maps to define the length of a map header.

The first and second map header labels have no semantic meaning with regard to length.
In fact, none of the labels are used at all.
Recomment type names.

This is mostly just whitespace reduction.
Use a macro for Odd Egg probabilities.
Add address labels used by Decompress.
Add labels for maps that reuse blockdata.
Use macros for both types of map headers.

This should make map headers much easier to edit than before.

Rather than occasionally being able to reuse blockdata semantically,
create a label for each map and attach it to some blockdata include.
This improves readability and reduces overhead when adding new maps.

The macro argument length bug doesn't seem to crop up here...
It looks like it only happens when an argument is over 16 characters
long and references a symbol that exists before the macro is invoked.
Merge pull request #257 from yenatch/map-headers

Map header macros and misc comments