Update Notes for v0.99

[list] [*] Added a new built-in campaign: Race Challenges [*] Added 11 more built-in circuits (with AI lines for all four built-in vehicles) [*] Added achievements (there are now 46 achivements to gain in various ways) [*] Added experience system - play any game modes to gain experience [*] Added rank system - advance in Race Challenges and Time Trials and gain enough experience to get promoted to new ranks [*] Added Progress Menu to see information about your stats, achievements and rank [*] The old Beta Race Campaign can still be opened by holding Shift and Ctrl when opening Race Challenges [*] Level Editor: Fixed level preview sometimes having slightly wrong colors [*] Level Editor: When changing the selected road marker or checkpoint, remembering which property folders were open [*] Level Editor: Added some more grass textures [*] Level Editor: Fixed a minor Z-fight flicker issue in pit templates [*] Gamepad thumbstick buttons to change the stats submodes are now disabled by default (to prevent accidental mode changes) [*] AI Editor: Level can now be changed after testing or training, too [*] AI Editor: Added a button to show info about all recordings in the current collection [*] AI players of different skill levels/groups are now blended better (smaller gaps between the levels) [*] Host: Automatic vehicle selection now works better with voting (and also disabled if there is not one fixed vehicle) [*] Fixed some HUD elements sometimes overlapping in an ugly way in the split-screen mode [*] Added new parts to the menu music [*] Miscellaneous other minor fixes and improvements [/list]