Initial implementation of TilePaletteEditor
State MVC framework has base classes

StateModel
StateView
StateController
State variable sharing

Using cvars
Scheduler clear > remove
Mouse.pos > Mouse.position
Use provided type for initializing default attributes on Models

Reduces typing a bit
Share tile_palette with map_editor and tile_palette_editor
Fixes TilePaletteEditor update and render
Scheduler#p_job_table and SchedulerJob tagging