No string refs (#766)

* Use callback ref instead of string ref

* Enable react/no-string-refs rule for xo

* Replace additional string refs

* Fix broken merge

lib/components/term.js

@@ -67,7 +67,7 @@ export default class Term extends Component {
       // this.term.CursorNode_ is available at this point.
       this.term.setCursorShape(props.cursorShape);
     };
-    this.term.decorate(this.refs.term);
+    this.term.decorate(this.termRef);
     this.term.installKeyboard();
     if (this.props.onTerminal) {
       this.props.onTerminal(this.term);
@@ -191,8 +191,8 @@ export default class Term extends Component {
   handleMouseDown(ev) {
     // we prevent losing focus when clicking the boundary
     // wrappers of the main terminal element
-    if (ev.target === this.refs.term_wrapper ||
-        ev.target === this.refs.term) {
+    if (ev.target === this.termWrapperRef ||
+        ev.target === this.termRef) {
       ev.preventDefault();
     }
   }
@@ -271,13 +271,20 @@ export default class Term extends Component {
 
   template(css) {
     return (<div
-      ref="term_wrapper"
+      ref={component => {
+        this.termWrapperRef = component;
+      }}
       className={css('fit')}
       onMouseDown={this.handleMouseDown}
       style={{padding: this.props.padding}}
       >
       { this.props.customChildrenBefore }
-      <div ref="term" className={css('fit', 'term')}/>
+      <div
+        ref={component => {
+          this.termRef = component;
+        }}
+        className={css('fit', 'term')}
+        />
       { this.props.url ?
         <webview
           src={this.props.url}

package.json

@@ -69,7 +69,6 @@
       "import/no-extraneous-dependencies": 0,
       "no-warning-comments": 0,
       "complexity": 0,
-      "react/no-string-refs": 0,
       "react/jsx-key": 0,
       "no-nested-ternary": 0,
       "react/jsx-no-bind": 0