0.3.2 balance changes + new item

Balance changes:

Bloody Knife:

        5 -> 6 damage increase

Red Heart:

        60% -> 30% heal

        60 -> 50 health increase

Parasitic Slug:

        0.95 -> 0.9 enemy bullet speed multiplier

Higher Stakes:

        1.2 -> 1.3 coins multiplier

        2 -> 1.5 enemy damage multiplier

        Also fixed bug where you also deal double damage

Shield Enemy:

        0.66 -> 1 enemy health (same as circles now)

Normal Boss:

        Bullet speed now scales like normal enemies (waves and items affect it now)

New item:

Medkit(common):

        40% heal

        20 health increase

Enemies can now spawn further and further away, increasing distance between them on later waves.