Various usability improvements (#665)

* Set password creator window title

* Fix TODO, help url is read from Info.plist instead of a string literal

* Remove width constraint for 'Set Defaults' button of password generator so text is not cropped

* Improve keyboard shortcuts
New entries can be created using cmd + n, while cmd + shift + n creates new groups. Creating new databases is probably done too rarely to warrant a keyboard shortcut.
Additionally the 'New' menu item now has a submenu containing actions to create new entries, groups and databases (fixing #405).

* Hook up keyboard shortcut cmd + backspace to delete action

* Use shorter date format in inspector and add special output for distant future

* Show date picker when expiration is activates for either groups or entries but no date set

* Prompt for key file pops up automatically when the field is selected using tab

* Focus title field when new groups are created (#606).

* Rename search method so text fields don't capture it (#531)

* Don't show empty tags

* Remove menu item used for debugging.

MacPass/MPAppDelegate.m

@@ -43,7 +43,7 @@
 #import <Sparkle/Sparkle.h>
 
 NSString *const MPDidChangeStoredKeyFilesSettings = @"com.hicknhack.macpass.MPDidChangeStoredKeyFilesSettings";
-
+NSString *const MPHelpURLKey = @"MPHelpURL";
 @interface MPAppDelegate () {
 @private
   MPDockTileHelper *dockTileHelper;
@@ -229,8 +229,8 @@ NSString *const MPDidChangeStoredKeyFilesSettings = @"com.hicknhack.macpass.MPDi
 }
 
 - (void)showHelp:(id)sender {
-  /* TODO: use Info.plist for URL */
-  [[NSWorkspace sharedWorkspace] openURL:[NSURL URLWithString:@"https://github.com/mstarke/MacPass"]];
+  NSString *urlString = [[NSBundle mainBundle] infoDictionary][MPHelpURLKey];
+  [[NSWorkspace sharedWorkspace] openURL:[NSURL URLWithString:urlString]];
 }
 
 - (void)checkForUpdates:(id)sender {