[v.0.2.3] Another Hot Fix! - Added pause menu & Level invisible wall issues!

Here goes another hot fix! 

Added Pause Menu

• You can access the pause menu by pressing "Esc" key
• In the pause menu, you can choose to...
  •  "Retry" - To reload the current stage
  • "Back to Main Menu" - Back to title screen

Fixed invisible wall issues

• At first, sometime, if the player got knocked back and they can get through the invisible wall. Making the boss unable to reach their attack to players.
• But now the issue was fixed!

Feel free to let me know if you encounter with any issues or just wanting to giving suggestions.
I will try to fix and release a hot fix ASAP.

Thank you!

- Kumotori