Merge pull request #2 from skittles1/addhighresgrid

Island sewers graphics fixes
Fix sector height typo in OPB lair.

Gate sector height was set to 204 instead of 274. Not sure if this was
deliberate or not, but I fixed it anyway.
Merge branch 'addhighresgrid' of https://github.com/skittles1/Meridian59_103 into addhighresgrid