Added a Makefile for test and install

by installing ticktick.sh in the PATH, you can have this usage:

    . `which ticktick.sh`

Makefile

@@ -0,0 +1,18 @@
+SRC_FILE := ticktick.sh
+BASH_PATH := $(shell which bash)
+INSTALL_PATH := $(shell dirname $(BASH_PATH))
+
+default: help
+
+help:
+	@echo
+	@echo 'make test - Run the TickTick test suite'
+	@echo 'make install - Install ticktick.sh (next to bash)'
+	@echo
+
+test:
+	(cd tests; ./runall.sh)
+
+install:
+	cp $(SRC_FILE) $(INSTALL_PATH)
+	chmod +x $(INSTALL_PATH)/$(SRC_FILE)