Delegate for return key when not completing token

When the user has the VENTokenField focused, and only has completed tokens, or no text at, tapping the return key now calls a new delegate method `tokenFieldDidReturn:`.

This is useful for the user to confirm entry of tokens, allowing the app to move focus to another text field or view.

`tokenField:didEnterText:` functionality has no change, and the code is written such that these two delegate methods are never called simultaneously.

README.md

@@ -24,10 +24,11 @@ Similar to ```UITableView```, ```VENTokenField``` provides two protocols: ```<VE
 ### VENTokenFieldDelegate
 This protocol notifies you when things happen in the token field that you might want to know about.
 
-* ```tokenField:didEnterText:``` is called when a user hits the return key on the input field.
+* ```tokenField:didEnterText:``` is called when a user hits the return key on the input field, completing a token.
 * ```tokenField:didDeleteTokenAtIndex:``` is called when a user deletes a token at a particular index.
 * ```tokenField:didChangeText:``` is called when a user changes the text in the input field.
 * ```tokenFieldDidBeginEditing:``` is called when the input field becomes first responder.
+* ```tokenFieldDidReturn:``` is called when the user hits the return key on the input field with no partial text entered.
 
 ### VENTokenFieldDataSource
 This protocol allows you to provide info about what you want to present in the token field.

VENTokenField/VENTokenField.h

@@ -32,6 +32,7 @@ NS_ASSUME_NONNULL_BEGIN
 - (void)tokenField:(VENTokenField *)tokenField didChangeText:(nullable NSString *)text;
 - (void)tokenFieldDidBeginEditing:(VENTokenField *)tokenField;
 - (void)tokenField:(VENTokenField *)tokenField didChangeContentHeight:(CGFloat)height;
+- (void)tokenFieldDidReturn:(VENTokenField *)tokenField;
 @end
 
 @protocol VENTokenFieldDataSource <NSObject>

VENTokenField/VENTokenField.m

@@ -548,10 +548,14 @@ - (NSString *)collapsedText
 
 - (BOOL)textFieldShouldReturn:(UITextField *)textField
 {
-    if ([self.delegate respondsToSelector:@selector(tokenField:didEnterText:)]) {
-        if ([textField.text length]) {
+    if ([textField.text length]) {
+        if ([self.delegate respondsToSelector:@selector(tokenField:didEnterText:)]) {
             [self.delegate tokenField:self didEnterText:textField.text];
         }
+    } else {
+        if ([self.delegate respondsToSelector:@selector(tokenFieldDidReturn:)]) {
+            [self.delegate tokenFieldDidReturn:self];
+        }
     }
 
     return NO;