Fixes from testing

Today, I worked on implementing some of the changes we decided after the testing session.

These were minor fixes, like stopping the character from being movable in third person view, balancing of towers and enemies or the player animation setup.

Furthermore, I updated and modified some of the UI:

- added a function to go back to the main menu at any time

- allow user to close the tower selection panel

- toggle additional information about the towers

- better scalability

Furthermore, it is now possible to actually win the game. One game lasts around 3 to 5 minutes. The spawners will stop after 3 mins of game time and once the player has defeated all enemies, the game is won.

After this, I prepared the scene for submission (removed testing objects, etc), colored the last remaining models, placed and moved a few of the decorative objects and added colliders to them etc. To improve the look and feel a little, I decided to change the lighting slightly to a warmer tone with far softer shadows. The title music now plays in-game and most actions (using sword, placing a tower, towers shooting) have sounds associated with them now.

Therefore, we nearly managed to implement all of the suggestions made in the testing session - obviously, some of them could be implemented to far greater detail, but this does not seem feasible for the purpose of a prototype.