background, explosion, boss

pohybujici se pozadi, vybuch nepratel, pridan boss a sance na spawn,
dalsi nepratele
Merge remote-tracking branch 'upstream/master'

Conflicts:
	www/script/main.js
	www/script/shoot.js
Merge remote-tracking branch 'upstream/master'
Merge pull request #6 from najezenejjezek/master

merge