Map models should use ChunkHead instead of Hash for Chunk references
Added Moon::Rect#inside?

This function is used for determining if a position is inside the rectangle
Addded Hash core_ext

Based off Rails' StrongParameters
Rehauling Map/Chunk system

Since the editor requires access to a Map's Chunks I've decided to add
an abtraction model called EditorMap and EditorChunk, these models
are designed specifically to work with the map editor.