Add .clearTerminal to clear the whole terminal, not just visible part of it (#6)

Author: Vadim Demedes

index.js

@@ -78,6 +78,15 @@ x.scrollUp = ESC + 'S';
 x.scrollDown = ESC + 'T';
 
 x.clearScreen = '\u001Bc';
+
+x.clearTerminal = process.platform === 'win32' ?
+	`${x.eraseScreen}${ESC}0f` :
+	// 1. Erases the screen (Only done in case `2` is not supported)
+	// 2. Erases the whole screen including scrollback buffer
+	// 3. Moves cursor to the top-left position
+	// More info: https://www.real-world-systems.com/docs/ANSIcode.html
+	`${x.eraseScreen}${ESC}3J${ESC}H`;
+
 x.beep = BEL;
 
 x.link = (text, url) => {

readme.md

@@ -117,7 +117,11 @@ Scroll display down one line.
 
 ### clearScreen
 
-Clear the terminal screen.
+Clear the terminal screen. (Viewport)
+
+### clearTerminal
+
+Clear the whole terminal, including scrollback buffer. (Not just the visible part of it)
 
 ### beep