Patch notes 4/18

Bug fixes:

1. Total enemies left would not always reset to the correct start-of-wave numbers after a player hit "Try Again"
2. Player health bar HUD was out of sync with the player health value so the player could die when the HUD still showed there was 1 block of health left
3. Fixed race condition where the last enemy death would sometimes count towards your score
4. High score now correctly displays in game over modal

Balance updates:

1. Shield now lasts for +2s longer (7s instead of 5s)