Added a sound effect that we already have for the "stage clear" music.

Maybe it's good enough, or maybe we need some better music for "you win"
Merge branch 'feature/issue/#86_Stage_clear_music_should_be_different_from_you_lost_music' into develop
made a very simple level, 1 spawn with 3 creeps, map that fits on 800x600
add missing file
configure the button label
more enemies at a higher rate
slightly adjusted mission menu layout
Merge branch 'feature/issue/#84_Tutorial_level' of https://github.com/nczempin/Turres-Monacorum into feature/issue/#84_Tutorial_level

Conflicts:
	love2d/data/menu/missions1.ini