Wild Pokemon functions and data

Replaced encounter rates with percent values
Added new constants denoting the number of wild Pokemon in the grass and water wild constructs
Annotated and relabeled the encounter generating functions
Renamed a WRAM address associaed with the temporary storage of the wild Pokemon's species
Moved spawn constants to constants/map_constants.asm for use anywhere in the disassembly

constants/pokemon_data_constants.asm

@@ -93,3 +93,9 @@ const_value SET 1
 	const ATK_GT_DEF
 	const ATK_LT_DEF
 	const ATK_EQ_DEF
+
+NUM_GRASSMON EQU 7
+NUM_WATERMON EQU 3
+
+GRASS_WILDDATA_LENGTH EQU (NUM_GRASSMON * 2 + 1) * 3 + 2
+WATER_WILDDATA_LENGTH EQU (NUM_WATERMON * 2 + 1) * 1 + 2