modding: Negative tile damage cannot heal more than max health

Mods with atlases that reference non-existent files will no longer cause crashes

By SomeTroglodyte:
- Reorg SpecialistAllocationTable

Improved settler AI  - By tuvus

By SeventhM:
- Fix Multiplayer Specatator being unable to move the screen
- Fix free stat buildings not giving unique stat buildings in certain cases