add function to quad tree to turn items into strings (for later saving to file)

fcore/parser/parser.md

@@ -0,0 +1,19 @@
+# Parsing
+
+The parsing functionality is for saving and loading from a custom file format.
+
+The BNF for the custom file format is below.
+
+Terminals are surrounded by `**` to the left and right. (rule)+ means "1 o more".
+
+```
+int ::= (0-9)+
+
+item ::= **{** int int int int int int int int **}**
+
+grid ::= int int **{** (item)+ **}**
+```
+
+The first two `int`s in the grid `int int **{** (item)+ **}**` always follow the order: `canvasWidth canvasHeight`.
+
+The large number of `int`s in the `item` always follows the order: `x y ex ey r g b a`.