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.
