add supertab plugin and vim-system-copy plugin

sources_forked/supertab/Makefile

@@ -0,0 +1,17 @@
+SHELL=/bin/bash
+
+all: dist
+
+dist:
+	@rm supertab.vmb 2> /dev/null || true
+	@vim -c 'r! git ls-files doc plugin' \
+		-c '$$,$$d _' -c '%MkVimball supertab .' -c 'q!'
+
+clean:
+	@rm -R build 2> /dev/null || true
+
+install: supertab.vmb
+	vim $< -c 'so %' -c 'q'
+
+uninstall:
+	vim -c 'RmVimball supertab.vmb' -c 'q'