Add make dist target

Produces a ZIP archive for release as dist/ndless.zip.

Makefile

@@ -20,3 +20,13 @@ build-%: %
 
 clean-%: %
 	$(MAKE) -C $< clean
+
+dist: all
+	rm -rf dist
+	mkdir -p dist/ndless/samples
+	cp Mozilla-Public-License-v1.1.html README.md dist/ndless/
+	cp ndless/calcbin/* dist/ndless/
+	rm dist/ndless/downgradefix_3.9*.tns dist/ndless/ndless_installer_3.9.0_classic.tns
+	cp ndless-sdk/samples/*/*.tns dist/ndless/samples/
+	rm dist/ndless/samples/freetype_demo.tns
+	cd dist && 7z a ndless.zip ndless