Add support for '-h' (help).

https://github.com/PaulStoffregen/teensy_loader_cli/pull/26

---
 teensy_loader_cli.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/teensy_loader_cli.c b/teensy_loader_cli.c
index d4a6cc5..0a06209 100644
--- a/teensy_loader_cli.c
+++ b/teensy_loader_cli.c
@@ -37,7 +37,8 @@ void usage(const char *err)
 {
 	if(err != NULL) fprintf(stderr, "%s\n\n", err);
 	fprintf(stderr,
-		"Usage: teensy_loader_cli --mcu=<MCU> [-w] [-h] [-n] [-b] [-v] <file.hex>\n"
+		"Usage: teensy_loader_cli --mcu=<MCU> [-h] [-w] [-n] [-b] [-v] <file.hex>\n"
+		"\t-h : Print this help message\n"
 		"\t-w : Wait for device to appear\n"
 		"\t-r : Use hard reboot if device not online\n"
 		"\t-s : Use soft reboot if device not online (Teensy3.x only)\n"
@@ -1081,6 +1082,7 @@ void parse_flag(char *arg)
 	int i;
 	for(i=1; arg[i]; i++) {
 		switch(arg[i]) {
+			case 'h': usage(NULL); break;
 			case 'w': wait_for_device_to_appear = 1; break;
 			case 'r': hard_reboot_device = 1; break;
 			case 's': soft_reboot_device = 1; break;
-- 
2.7.4