New Stage! New Enemies! New Artifacts! And more..

- Added stage: 'Plains of Terror', but without the boss fight (yet).
- Added enemies: 'Rot', 'Clawer', 'Evil Eye', 'Blood Beast', 'Angel of Pain'.
- Added achievements: 'Rot Slayer', 'Clawer Slayer', 'Evil Eye Slayer', 'Angel of Pain Slayer', 'Maestro'.
- Optimized level previews to load stages menu faster.
- Made 'Animal Domination' stronger.
- Added stronger buff to enemies once 'The Inevitable' spawn.
- Added better reward for defeating 'The Inevitable' (also made them slightly stronger).
- Made 'Ballistra' slightly stronger.
- Added artifacts: 'Toothpick', 'Energy Bar', 'Robber Gloves', 'Fire Extinguisher', 'Thawing Potion', 'Antidote'.
- Made 'Rogue' ultimate weaker.
- Fixed 'Daily Challenge' title in "Played Stages" stats.
- Fixed broken 'Travel East' mission.
- Made 'Travel East' out of circle damage bigger and ignore armor.
- Tiny graphics improvements.
- Switched completed / incomplete achievement background colors to match the colors in Powerups.
- Added 'Breach And Disrupt' mission to Daily Challenges.