Re-commit of "Fixed order of includes in all source files"

This reverts commit 94657284973f4037596bae468ebfbee5c217e02b.
Moved MAX_CARTS and NEW_CARTS defines into common/mmo.h

- Fixes bugreport:8184, allowing re-commit of
  94657284973f4037596bae468ebfbee5c217e02b

Signed-off-by: Haru <haru@dotalux.com>
Follow-up to 5f1529083ad1f35a3ac66cc041ee74d6db2f3552

- Now the map-server returns nonzero even on nomral runs (or
  --run-once) if any script failed loading.

Signed-off-by: Haru <haru@dotalux.com>