Space Raid v2a

Probably going to be the last update for this (excluding bug fixes).

- Slight changes to Hard Mode.
- Shotgun weapon now fires every 1.4 seconds instead of 1.6.
- Laser weapon now applies on-hit effects for every enemy pierced.
- Reduced the effectiveness of Engine Booster upgrades down to 7% and 15%.
- Fixed White Missile Launcher firing every 5 seconds instead of 6 (as stated in the description).