Powerups

[pixlmaster]

Basic Power-up layout
1.Power-up(red circle) spawns in the grey circle for 3 seconds
2.after each power-up, cool-down of 6-9 seconds added.
3.power up disappears on touching.

changes
1.added relevant constants in constant.py
2. added new class for power-ups in global_objects.py.
3.modified render function to update and check touching.

things to be added.

1. Powerups on touching just disappear and don't do anything.
   2.multiple types of power-ups need to be added( this will need sprites)

[thealphadollar]

LGTM. Nice. Please update the readme by creating a section of power-ups available and adding those you implemented here.

Also resolve the merge conflict.

[amrit-choudhary]

add .pyc to .gitignore

[thealphadollar]

@pixlmaster Please resolve the merge conflicts.