add image selector field type, modal component, and new snippet widgets

shared/naturalcrit/codeEditor/helpers/widget-elements/modal/modal.jsx

@@ -0,0 +1,49 @@
+require('./modal.less');
+const React = require('react');
+const createClass = require('create-react-class');
+
+const Modal = createClass({
+	getDefaultProps : function () {
+		return {
+			header : '',
+			save   : ()=>{},
+		};
+	},
+
+	getInitialState : function() {
+		return {
+			visible : false,
+		};
+	},
+
+	setVisible : function(visible) {
+		this.setState({
+			visible
+		});
+	},
+
+	save : function() {
+		this.props.save();
+		this.setVisible(false);
+	},
+
+	render : function () {
+		const { children, header } = this.props;
+		const { visible } = this.state;
+		return <React.Fragment>
+			{visible ? <div className={'bg-cover'}>
+				<div className={'modal'}>
+					<h1>{header}</h1>
+					<hr/>
+					{children}
+					<div className={'action-row'}>
+						<button id={'save'} onClick={()=>this.save()}>Save</button>
+						<button id={'cancel'} onClick={()=>this.setVisible(false)}>Cancel</button>
+					</div>
+				</div>
+			</div> : null}
+		</React.Fragment>;
+	}
+});
+
+module.exports = Modal;