Special parsing for tile id `0`

[ace-dent]

Feature / enhancement request: It is desirable to copy & paste tile data from external sources, into the Game Data of the main Bitsy editor. This may be from other graphic libraries, converter programs, etc. However, it is unknown to an external source how to number the base36 id, to avoid colliding with existing id's in the Bitsy editor.

Currently tile id zero (TIL 0) is reserved, and treated as blank in the game map data. It should not exist in the tile set.

Proposal: On parsing updated (copy&pasted) tile data, any tiles assigned an id of 0, should be assigned new id's, based on current automatic generation.

e.g.

TIL 0
00000000
00001010
00000100
00000000
00000000
10100000
01000000
00000000
NAME grass

TIL 0
00000000
00000000
00000000
00000000
00000100
01001000
00101000
00000000
NAME tuffet

– Might be assigned TIL b and TIL c.

I'm not sure whether this requirement exists for other object types...