v0.2.1 small patch and video tutorial for the editor — Nebula Flow Steam update #713558

Hey! Here's a quick hotfix update following the previous v0.2.0 patch. Game: Fixed game sometimes crashing when launching tutorial. Fixed note generation bug where switch joined note would generate a stray move. Improved path render underneath playing character. Editor: Fixed editor crash when using a negative time position. Level editor now uses the "custom_levels" directory by default when opening/saving a level for the first time. 5 lanes now rendered when testing level with grid lines displayed. Fixed various small bugs and improved UX. Also, here is a video tutorial to start using Nebula Flow's level editor: