fix: change toolbar API to match top level onViewChange prop name

* Changed Toolbar prop name to resolve error when creating custom component toolbar

* Modified generated toolbar component in Calendar to have onView property instead of onViewChange

Author: mmmbacon

src/Calendar.js

@@ -859,7 +859,7 @@ class Calendar extends React.Component {
             view={view}
             views={viewNames}
             label={label}
-            onViewChange={this.handleViewChange}
+            onView={this.handleViewChange}
             onNavigate={this.handleNavigate}
             localizer={localizer}
           />

src/Toolbar.js

@@ -10,7 +10,7 @@ class Toolbar extends React.Component {
     label: PropTypes.node.isRequired,
     localizer: PropTypes.object,
     onNavigate: PropTypes.func.isRequired,
-    onViewChange: PropTypes.func.isRequired,
+    onView: PropTypes.func.isRequired,
   }
 
   render() {
@@ -51,7 +51,7 @@ class Toolbar extends React.Component {
   }
 
   view = view => {
-    this.props.onViewChange(view)
+    this.props.onView(view)
   }
 
   viewNamesGroup(messages) {