HammerHelm update for 14 December 2019

This is a small update that includes an auto-sprint button. The default is set to L, but you can change it in the options. The reason for the small build today is because I updated to the most recent release of HammerHelm's engine, Unity. I've tested the game for a while and feel like it's in good shape, but engine updates can sometimes cause unforeseen issues, so I wanted to release something with a minor change just in case.