Document and add example of promptLabel as a function

README.md

@@ -33,7 +33,7 @@ Properties you can pass to the console element
 | complete?			| function(words: string[], cursor: number, prompt: string): string[]	| Return a list of possible completions given a list of (`words`), index of the word containing the cursor (`cursor`) , and the full prompt text (`prompt`).
 | continue?			| function(prompt: string): bool										| Return a boolean indicating whether to continue asking for user input on a newline given the current prompt text (`prompt`).
 | handler			| function(command: string): any										| Handle a command (`command`), logging data with `this.log()` or `this.logX()`, and calling `this.return()` when finished.
-| promptLabel?		| string																| String displayed to prompt user for input.
+| promptLabel?		| string | function(): string											| String displayed to prompt user for input.
 | welcomeMessage?	| string																| Initial message displayed after mount.
 
 ## Public members

example/echo.tsx

@@ -4,17 +4,32 @@ import * as React from 'react';
 import * as ReactDOM from 'react-dom';
 import Console from '../src/react-console.tsx';
 
-class EchoConsole extends React.Component<{},{}> {
+interface EchoConsoleState {
+	count: number;
+}
+class EchoConsole extends React.Component<{},EchoConsoleState> {
+	constructor(props: {}) {
+		super(props);
+		this.state = {
+			count: 0,
+		};
+	}
 	child: {
 		console?: Console,
 	} = {};
 	echo = (text: string) => {
 		this.child.console.log(text);
-		this.child.console.return();
+		this.setState({
+			count: this.state.count+1,
+		}, this.child.console.return);
+	}
+	promptLabel = () => {
+		return this.state.count + "> ";
 	}
 	render() {
 		return <Console ref={ref => this.child.console = ref}
 			handler={this.echo}
+			promptLabel={this.promptLabel}
 			autofocus={true}
 		/>;
 	}