Bugfix: Gestures works again.
Insert 'use strict'; and make some bugfixes because of it. These variables must be moved into some 'classes'.
Merge pull request #7 from matinhpfsc/EndlessGame

Merge bugfixes for gestures and syntax changes needed by introducing 'use strict'; on a few more scripts.
Move Vector2d to own file and provide test cases

- enable test automation infrastructure (grunt test)
- moved Vector2d code to new script
- added test suite for Vector2d

Important note: A dependency was updated in the build system, so please run
'npm install' to get the correct dependencies installed!