Bug: flags member of MapHeader struct is not handled correctly for pokeemerald

[huderlem]

In Ruby, MapHeader.flags is only used for enabling the map name popup. In Emerald, it is a bitfield that holds 4 values:
Bit 0: biking allowed
Bit 1: escape rope allowed
Bit 2: running shoes allowed
Bit 3: map name popup enabled

Porymap needs to show these extra checkboxes for Emerald, and update the save logic accordingly.

[huderlem]

ebdab42