Step towards target-based building

Makefile

@@ -1,6 +1,14 @@
 all:
-	python makepanda/makepanda.py --everything
+	python makepanda/makepanda.py --everything --target all
+panda3d:
+	python makepanda/makepanda.py --everything --target panda3d
+plugins:
+	python makepanda/makepanda.py --everything --target plugins
+installer:
+	python makepanda/makepanda.py --everything --target installer
 install:
 	python makepanda/installpanda.py
 clean:
 	rm -rf built
+
+.PHONY: all install clean