Automatic tile transition resolution

[DjThunder]

Provide an automatic tile transition resolution between different groups when supported by the tile sheet.

Example:

• Forest - Forest Ground - Ground

By using output from #164 and the groups configuration, it should be possible to resolve transitions automatically with raw tiles (CENTER version), and replace it with its right transition.

An alternative is to store using a specific way the tile sheet, but here the goal is to be tile sheet order independent, as they can be automatically generated from a level rip.

Note: When analyzing existing transitions, consider tiles on map border as same group in order to avoid false transition.

[DjThunder]

Review transition system to support both sides (ex: ground - tree, tree - ground). Instead of having two groups (ground, tree), there must be three groups (ground, tree, groundtree), where the third group contains tiles used for transition between the two groups.

[DjThunder]

Transitive dependencies must also be handled.
Use case:

• Put water over forest
• Around water dot, transitive transition must be used to resolve the unexisting water - tree transition
• Use water - ground, and then ground - tree