Explore: compact state URLs

- allow positional state array in URL
- key-based parsing as fallback
- fix issue where split state was kept in URL after closing split

public/app/features/explore/Explore.tsx

@@ -275,7 +275,6 @@ export class Explore extends React.PureComponent<ExploreProps, ExploreState> {
     const { onChangeSplit } = this.props;
     if (onChangeSplit) {
       onChangeSplit(false);
-      this.saveState();
     }
   };
 
@@ -292,7 +291,6 @@ export class Explore extends React.PureComponent<ExploreProps, ExploreState> {
     if (onChangeSplit) {
       const state = this.cloneState();
       onChangeSplit(true, state);
-      this.saveState();
     }
   };
 
@@ -534,12 +532,12 @@ export class Explore extends React.PureComponent<ExploreProps, ExploreState> {
               </a>
             </div>
           ) : (
-              <div className="navbar-buttons explore-first-button">
-                <button className="btn navbar-button" onClick={this.onClickCloseSplit}>
-                  Close Split
+            <div className="navbar-buttons explore-first-button">
+              <button className="btn navbar-button" onClick={this.onClickCloseSplit}>
+                Close Split
               </button>
-              </div>
-            )}
+            </div>
+          )}
           {!datasourceMissing ? (
             <div className="navbar-buttons">
               <Select

public/app/features/explore/Wrapper.tsx

@@ -38,10 +38,17 @@ export class Wrapper extends Component<WrapperProps, WrapperState> {
 
   onChangeSplit = (split: boolean, splitState: ExploreState) => {
     this.setState({ split, splitState });
+    // When closing split, remove URL state for split part
+    if (!split) {
+      delete this.urlStates[STATE_KEY_RIGHT];
+      this.props.updateLocation({
+        query: this.urlStates,
+      });
+    }
   };
 
   onSaveState = (key: string, state: ExploreState) => {
-    const urlState = serializeStateToUrlParam(state);
+    const urlState = serializeStateToUrlParam(state, true);
     this.urlStates[key] = urlState;
     this.props.updateLocation({
       query: this.urlStates,