Makefile: Support installing individual modules with "install MOD=<name>".

Makefile

@@ -4,7 +4,11 @@ all:
 
 # Installs all modules to a lib location, for development testing
 install:
-	mkdir -p $(PREFIX)
-	for d in $$(find -maxdepth 1 -type d ! -name ".*"); do \
-	    (cd $$d; cp -r $$(find . -name "*.py") $(PREFIX)); \
-	done \
+	@mkdir -p $(PREFIX)
+	@if [ -n "$(MOD)" ]; then \
+	    (cd $(MOD); cp -r * $(PREFIX)); \
+	else \
+	    for d in $$(find -maxdepth 1 -type d ! -name ".*"); do \
+	        (cd $$d; cp -r * $(PREFIX)); \
+	    done \
+	fi