dashboard: CPU, memory, diskIO and traffic on the footer (#15950)

* dashboard: footer, deep state update

* dashboard: resolve asset path

* dashboard: prevent state update on every reconnection

* dashboard: fix linter issue

* dashboard, cmd: minor UI fix, include commit hash

* dashboard: gitCommit renamed to commit

* dashboard: move the geth version to the right, make commit optional

* dashboard: memory, traffic and CPU on footer

* dashboard: fix merge

* dashboard: CPU, diskIO on footer

* dashboard: rename variables, use group declaration

* dashboard: docs

dashboard/assets/components/ChartRow.jsx

@@ -0,0 +1,57 @@
+// @flow
+
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+import React, {Component} from 'react';
+import type {ChildrenArray} from 'react';
+
+import Grid from 'material-ui/Grid';
+
+// styles contains the constant styles of the component.
+const styles = {
+	container: {
+		flexWrap: 'nowrap',
+		height:   '100%',
+		maxWidth: '100%',
+		margin:   0,
+	},
+	item: {
+		flex:    1,
+		padding: 0,
+	},
+}
+
+export type Props = {
+	children: ChildrenArray<React$Element<any>>,
+};
+
+// ChartRow renders a row of equally sized responsive charts.
+class ChartRow extends Component<Props> {
+	render() {
+		return (
+			<Grid container direction='row' style={styles.container} justify='space-between'>
+				{React.Children.map(this.props.children, child => (
+					<Grid item xs style={styles.item}>
+						{child}
+					</Grid>
+				))}
+			</Grid>
+		);
+	}
+}
+
+export default ChartRow;