makefile for simple testing

This is hard to use within Travis-ci.com because that uses
build variants.
diff --git a/dev.makefile b/dev.makefile
new file mode 100644
index 0000000..7a96af8
--- /dev/null
+++ b/dev.makefile
@@ -0,0 +1,14 @@
+all: build test-amalgamate
+
+build:
+	mkdir -p build/debug
+	cd build/debug; cmake -DCMAKE_BUILD_TYPE=debug -DJSONCPP_LIB_BUILD_SHARED=OFF -G "Unix Makefiles" ../..
+	make -C build/debug
+
+# Currently, this depends on include/json/version.h generated
+# by cmake.
+test-amalgamate: build
+	python2.7 amalgamate.py
+	python3.4 amalgamate.py
+
+.PHONY: build