Created QuadTree.cs..

Only the constructor for now.
GDComp.cs now has a GetRect() function.
Created GetIndex() in QuadTree.cs.
More functions for QuadTree.cs..

GetAll() to get one node's leaves + it's child's.
Get Quadrant() to get one node quadrant's leaves.
UpdateQuadrant() to update a quadrant (For thread safe updating).
Index enum for safe indexing.
Added 3 more functions to QuadTree.cs..
Split() which creates 4 child nodes.
Clear() which clears the called node and all it's child nodes.
Inster() part I. Inserts an object if it fits in a child node.
Update to .gitignore.