Add option to show one livestream entry per channel for slow machines like the raspberry pi

new option „Show Livestream Information“
- default value is true (same behavior as before)
- if disabled the current livestream information is not parsed from the
website, but one entry per channel is shown with the only information
beeing the channel name
additional improvements
- the channel banner is set with the channel logo
- translated settings text
- show description per livestream instead of hardcoded string
- replace channel name found the by the parser with full channel name