Reverted commit 347292d8666dbaed6e97f28737571d88a9be1d8f
Reverted commit ec709efaa3db6d5b9b4fffd118e72ff6074adcce.
Reverted commit 0c10c9db7f6b536f7cb02e4a4ece26777d9fd864.
Reverted commit 8f112d669cdaf2b24b8e3c168bb8f1edd5c7de3b.
Changed custom D1X license to GPLv3
corrected typo in COPYING.txt (it's to its)
Disallow using signed offsets with partial_range
Add dummy parameter version to D2 matcen_info_read
Remove broken TRIGGER_MATCEN check

D1X sets flags to TRIGGER_MATCEN, not type.
Remove write-only D1X trigger field type
Use symbolic constants for trigger types
Add optional offset to partial_range
Add __attribute__((warn_unused_result)) to partial_range
Remove unused v19_door
Get rid of MarkerPoint

Hope MT's ambiguous "horrible bug" is long gone since he never said what
it was.
Remove write-only variable tmap_times_used
Remove useless Sounds[] counting loop
Skip useless sin computation
Use std::swap instead of inline swap
Remove C-only warnings