Charts: Stroke style of axis ticks and grid lines is now set
independently.
Security: Fixed XSS vulnerability in session selection dropdown.
Merge branch '1.0-stable'

Conflicts:
	src/main/websources/lib/thm.de/arsnova/presenter/ui/sessionControls.js
Changed version for release: 1.0.6
Changed version for development: 1.0.7-SNAPSHOT
Ignore commits concerning version changes for future merges.