adding comments, removing cruft from Makefile

Makefile

@@ -1,14 +1,24 @@
-BASE = $(PWD)
+# sets mxmlc to just the basename "mxmlc"
+# if not overridden in command line like so:
+#    make MXMLC=/path/to/my/mxmlc
 MXMLC ?= mxmlc
+
+
+# define all target swf paths (which don't yet exist if
+# they've never been built)
 SWFS = $(patsubst %.mxml,%.swf,$(wildcard [0-9]*-*/*.mxml))
 
 
+# define an implicit build rule for any file matching %.swf,
+# using the $< (input) and $@ (output) automatic variables
 %.swf : %.mxml
 	$(MXMLC) $< -warnings -output $@
 
 
+# build all expected swf files
 all: $(SWFS)
 
 
+# remove all swf files in the tree
 clean:
 	find -name \*.swf -exec rm {} \;