Add clear-screen functionality

modified:   README.md
	modified:   src/main.c

README.md

@@ -85,6 +85,7 @@ for the user to press a key before it starts the decryption sequence.
 ls -l / | nms
 ls -l / | nms -a           // Set auto-decrypt flag
 ls -l / | nms -f green     // Set foreground color to green
+ls -l / | nms -c           // Clear screen
 ```
 
 #### Command Line Options
@@ -100,6 +101,13 @@ This option sets the foreground color of the decrypted text to the color
 specified. Valid options are white, yellow, black, magenta, blue, green,
 or red. This is blue by default.
 
+`-c`
+
+This option clears the screen prior to printing any output. Specifically,
+it saves the state of the terminal (all current output), and restores it
+once the effect is comlpeted. Note that when using this option, `nms` requires
+the user to press a key before restoring the terminal.
+
 License
 -------
 

src/main.c

@@ -12,7 +12,7 @@ int main(int argc, char *argv[]) {
 	char *input = NULL;
 
 	// Processing command arguments
-	while ((o = getopt(argc, argv, "f:av")) != -1) {
+	while ((o = getopt(argc, argv, "f:acv")) != -1) {
 		switch (o) {
 			case 'f':
 				nms_set_foreground_color(optarg);
@@ -20,6 +20,9 @@ int main(int argc, char *argv[]) {
 			case 'a':
 				nms_set_auto_decrypt(1);
 				break;
+			case 'c':
+				nms_set_clear_scr(1);
+				break;
 			case 'v':
 				printf("nms version " VERSION "\n");
 				return 0;