Reorganize the makefile and remove yellow targets.

Makefile

@@ -1,41 +1,10 @@
-# Build Red/Blue. Yellow is WIP.
+# python 2.7
-roms := pokered.gbc pokeblue.gbc
-
-
-.PHONY: all clean red blue yellow compare
-
-all:    $(roms)
-red:    pokered.gbc
-blue:   pokeblue.gbc
-yellow: pokeyellow.gbc
-
-versions := red blue yellow
-
-
-# Header options for rgbfix.
-dmg_opt =  -jsv -k 01 -l 0x33 -m 0x13 -p 0 -r 03
-cgb_opt = -cjsv -k 01 -l 0x33 -m 0x1b -p 0 -r 03
-
-red_opt    = $(dmg_opt) -t "POKEMON RED"
-blue_opt   = $(dmg_opt) -t "POKEMON BLUE"
-yellow_opt = $(cgb_opt) -t "POKEMON YELLOW"
-
-
-
-# If your default python is 3, you may want to change this to python27.
 PYTHON := python
 
 # md5sum -c is used to compare rom hashes. The options may vary across platforms.
 MD5 := md5sum -c --quiet
 
 
-# The compare target is a shortcut to check that the build matches the original roms exactly.
-# This is for contributors to make sure a change didn't affect the contents of the rom.
-# More thorough comparison can be made by diffing the output of hexdump -C against both roms.
-compare: red blue
-	@$(MD5) roms.md5
-
-
 # Clear the default suffixes.
 .SUFFIXES:
 .SUFFIXES: .asm .o .gbc .png .2bpp .1bpp .pic
@@ -46,16 +15,19 @@ compare: red blue
 # Suppress annoying intermediate file deletion messages.
 .PRECIOUS: %.2bpp
 
-# Filepath shortcuts to avoid overly long recipes.
+.PHONY: all clean red blue compare
+
+
 poketools := extras/pokemontools
 gfx       := $(PYTHON) $(poketools)/gfx.py
-pic       := $(PYTHON) $(poketools)/pic.py
+2bpp      := $(gfx) 2bpp
+1bpp      := $(gfx) 1bpp
+pic       := $(PYTHON) $(poketools)/pic.py compress
 includes  := $(PYTHON) $(poketools)/scan_includes.py
 
+versions := red blue
 
-
+# Collect file dependencies for objects in red/ and blue/.
-# Collect file dependencies for objects in red/, blue/ and yellow/.
-# These aren't provided by rgbds by default, so we have to look for file includes ourselves.
 $(foreach ver, $(versions), \
 	$(eval $(ver)_asm := $(shell find $(ver) -iname '*.asm')) \
 	$(eval $(ver)_obj := $($(ver)_asm:.asm=.o)) \
@@ -66,24 +38,43 @@ $(foreach obj, $(all_obj), \
 )
 
 
-%.png:  ;
+roms := pokered.gbc pokeblue.gbc
-%.2bpp: %.png  ; @$(gfx) 2bpp $<
-%.1bpp: %.png  ; @$(gfx) 1bpp $<
-%.pic:  %.2bpp ; @$(pic) compress $<
 
-# Assemble source files into objects.
+all:    $(roms)
-$(all_obj): $$*.asm $$($$*_dep)
+red:    pokered.gbc
-	rgbasm -h -o $@ $*.asm
+blue:   pokeblue.gbc
+
+# For contributors to make sure a change didn't affect the contents of the rom.
+compare: red blue
+	@$(MD5) roms.md5
+
+clean:
+	rm -f $(roms) $(all_obj) $(roms:.gbc=.sym)
+	find . \( -iname '*.1bpp' -o -iname '*.2bpp' -o -iname '*.pic' \) -exec rm {} +
+
+
+# Don't fix halts.
+asm_opt = -h
 
 # Make a symfile for debugging.
 link_opt = -n poke$*.sym
 
-# Link objects together to build a rom.
+# Header options for rgbfix.
+dmg_opt =  -jsv -k 01 -l 0x33 -m 0x13 -p 0 -r 03
+red_opt    = $(dmg_opt) -t "POKEMON RED"
+blue_opt   = $(dmg_opt) -t "POKEMON BLUE"
+
+
+%.png:  ;
+%.2bpp: %.png  ; @$(2bpp) $<
+%.1bpp: %.png  ; @$(1bpp) $<
+%.pic:  %.2bpp ; @$(pic)  $<
+
+# Assemble source files into objects.
+$(all_obj): $$*.asm $$($$*_dep)
+	rgbasm $(asm_opt) -o $@ $*.asm
+
+# Link objects to produce a rom.
 poke%.gbc: $$(%_obj)
 	rgblink $(link_opt) -o $@ $^
 	rgbfix $($*_opt) $@
-
-
-clean:
-	rm -f $(roms) $(all_obj) poke*.sym
-	find . \( -iname '*.1bpp' -o -iname '*.2bpp' -o -iname '*.pic' \) -exec rm {} +