选中的节点第二次点击时还是选中，不自动取消选中

demo/demolist/Demo1.js

@@ -51,6 +51,7 @@ class Demo1 extends Component {
 					defaultCheckedKeys = {this.state.defaultCheckedKeys}
 					checkStrictly
 					showIcon
+					cancelUnSelect={true}
 					onSelect={this.onSelect} onCheck={this.onCheck}
 					onDoubleClick={this.onDoubleClick}
 	      >

docs/api.md

@@ -18,6 +18,7 @@
 |checkStrictly|精细的检查每个节点|bool|false
 |defaultSelectedKeys|指定选中的节点key|String[]|[]
 |selectedKeys|指定选中的节点keys(controlled)|String[]|-
+|cancelUnSelect|选中的节点第二次点击时还是选中，不自动取消选中|bool|false
 |showLine|是否显示连接线|bool|false
 |openIcon|自定义展开节点图标的名称[参考这里](http://bee.tinper.org/bee-icon)String[]|-
 |closeIcon|自定义关闭节点图标的名称[参考这里](http://bee.tinper.org/bee-icon)String[]|-

src/Tree.js

@@ -279,16 +279,28 @@ class Tree extends React.Component {
     const eventKey = treeNode.props.eventKey;
     const index = selectedKeys.indexOf(eventKey);
     let selected;
-    if (index !== -1) {
+    //cancelUnSelect为true时第二次点击时不取消选中
-      selected = false;
+    if(props.cancelUnSelect){
-      selectedKeys.splice(index, 1);
+      if (index == -1) {
-    } else {
+        selected = true;
-      selected = true;
+        if (!props.multiple) {
-      if (!props.multiple) {
+          selectedKeys.length = 0;
-        selectedKeys.length = 0;
+        }
+        selectedKeys.push(eventKey);
+      }
+    }else{
+      if (index !== -1) {
+        selected = false;
+        selectedKeys.splice(index, 1);
+      } else {
+        selected = true;
+        if (!props.multiple) {
+          selectedKeys.length = 0;
+        }
+        selectedKeys.push(eventKey);
       }
-      selectedKeys.push(eventKey);
     }
+    
     const selectedNodes = [];
     if (selectedKeys.length) {
       loopAllChildren(this.props.children, (item) => {