Update - Subjects, collaborative editing and more

Enhancements - Subjects - you can now categorise your course(s) into subjects/topics of interest. - Collaborative editing - you can now invite other users to have permission to edit your course. You can find this option under Course Settings. Please ensure you add the correct user. We cannot offer support for courses which have been edited or in someway broken by other users. - Improved performance - we improved the loading speed of several pages, including course selection screen and and table view editing. - Ideas: You can now vote for your favourite idea. Help us prioritise. Visit the help section and click ideas, or visit memory.com/ideas Bug fixes - ensure questions are reloaded in new order after reordering questions - improve question editing whilst in chapter mode and fix crash when deleting a question from that screen - fixed image zoom in flashcard swipe mode - fixed an issue where images would not always delete correctly from questions