Simultaneous downloads

• Download multiple broadcasts simultaneously if more than one live stream is active
• Fix download date in output filename
• Update user agent string
• Rename monitor.py module to channel.py
• Minor fixes

Full Changelog: v0.1.1...v0.2.0

v0.1.1

What's Changed

• Fix warnings when number of video Ids differ from the previous state in #84

Full Changelog: 0.1.0...v0.1.1