Restore default keys and a few other things

The next update will be ready in about two hours. Here's what it includes: 1. Added a button to restore default keys in the controls menu. 2. In the controls menu, mouse buttons will now be named 'RMB' (Right Mouse Button) and 'MMB' (Middle Mouse Button) instead of 'Mouse1' and 'Mouse2'. 3. The tutorial has been corrected to display 'Middle Mouse Button' for free look since it was still showing 'Right Mouse Button' as assigned to this action. This was an oversight after the default keys were changed. 4. Corrected the symbol of the healer in Cathlana, so it now displays the correct one. 5. Fixed a few typos. Upcoming update: 1. I'm currently working on a function that shows whether all enemies have been defeated in an area and if all loot has been collected. However, this feature is not ready yet. I'm hoping to have it available by the end of the week. 2. I will also add the ability to individually adjust the volume of combat music and out-of-combat world ambiance since they are currently controlled by the same slider