Glass Hearts demo visual update and discount

Hey,

We've improved the visuals of the Glass Hearts demo using the graphics made for the full version. As thanks to everyone who plays the new demo there is a 20% discount code at the end for anyone who would like to get early access to the full game.

Improvements list:

- A fully animated main menu screen featuring Kai, our mc!

- Guard Sho and Guard Zhao now appear as full sprites

- The two nurses pestering Moyu also get their full sprites

- A number of sound effects and bgm tracks now included