Fix off-by-1 in Get Game Info: Get Tile bitfield

[tsdko]

According to tpc.exe bitfield offsets for Get Tile ID start at 0, not 1. I've modified the test map from #3330 and confirmed (on RPG_RT version 211010, im, patch_en) the command behaves as expected only if the initial offset is 0.

Modified maps with added cases for indirect inputs: Modified test map (correct behavior on RPG_RT, wrong on current EasyRPG) Modified test map adjusted for current EasyRPG (wrong behavior on RPG_RT, works on current EasyRPG) Both maps exhibit the same behavior on RPG_RT and EasyRPG (i.e. the 2nd one produces the exact same wrong results on both) with this PR applied.

[Ghabry]

Jenkins: test this please