Strings fixes for 3.3.1

Author: jleyva

lang/en/local_moodlemobileapp.php

@@ -399,7 +399,6 @@
 $string['mma.messages.contactlistempty'] = 'The contact list is empty';
 $string['mma.messages.contactname'] = 'Contact name';
 $string['mma.messages.errordeletemessage'] = 'Error while deleting the message.';
-$string['mma.messages.erroruseronlyacceptsmessagefromcontacts'] = '';
 $string['mma.messages.errorwhileretrievingcontacts'] = 'Error while retrieving the contacts from the server.';
 $string['mma.messages.errorwhileretrievingdiscussions'] = 'Error while retrieving the discussions from the server.';
 $string['mma.messages.errorwhileretrievingmessages'] = 'Error while retrieving the messages from the server.';
@@ -471,7 +470,7 @@
 $string['mma.mod_imscp.showmoduledescription'] = 'Show description';
 $string['mma.mod_label.label'] = 'Label';
 $string['mma.mod_label.taptoview'] = 'Tap to view the label.';
-$string['mma.mod_lesson.errorprefetchrandombranch'] = 'This lesson contains a jump to a random content page, it cannot be attempted in the app until it has been started in web.';
+$string['mma.mod_lesson.errorprefetchrandombranch'] = 'This lesson contains a jump to a random content page. It can\'t be attempted in the app until it has been started in a web browser.';
 $string['mma.mod_lesson.errorreviewretakenotlast'] = 'This attempt can no longer be reviewed because another attempt has been finished.';
 $string['mma.mod_lesson.finishretakeoffline'] = 'This attempt was finished offline.';
 $string['mma.mod_lesson.retakefinishedinsync'] = 'An offline attempt was synchronized. Do you want to review it?';