add Help option

src/mkg1m/main.cpp

@@ -11,6 +11,15 @@
 
 using namespace std;
 
+string getHelpString(){
+	return "\nUsage : mkg1m input-file [OPTION]\n\n"
+    "  -o output\t\tWrite output to file.\n"
+    "  -l lib\t\tSearch the library named library.\n"
+    "  -L dir\t\tadd all the libraries in the folder dir.\n"
+    "  -v\t\t\tShow version then exit\n"
+    "  -h\t\t\tShow help then exit\n";
+}
+
 string getVersionString(){
 	string str;
 
@@ -70,6 +79,9 @@ int main(int argc,char *argv[])
 			case 'v':
 				cout << getVersionString();
 				return 0;
+			case 'h':
+				cout << getHelpString();
+				return 0;
 			case '?':
 				if (optopt == 'o')
 					fprintf (stderr, "Option -%c requires an argument.\n", optopt);