Fix AI concurrency bug
remove duplicated attribute
make powerups indestructible

otherwise they are destroyed by bombs
Add 'powerup received' messages to views
add fully playable grid3.json
Remove unnecessary code
Add client controls help menu
Center server dialogs on frame
Enemy to keep update_delay attribute
remove unused import
fix syncronization error in tests
Move units to separate package
Merge pull request #111 from oharaandrew314/#106-milestone-prep

#106 milestone prep