Non-subscribed channels support
This release adds support for non-subscribed YT channels (Issue #3). Extra channels can now be checked for new videos using the include_extra_channels and the extra_channel_handles parameters. This is implemented similarly to how caption filtering has been implemented in v1.8.0.
include_extra_channels: Triggers the check for extra channels. If set to True, the channels listed in the following parameter will be taken into account in the rest of the program, even if you're not subscribed to them.
extra_channel_handles: Additional YT channels to check. Channels are identified by their handle. Videos from these channels will be processed in the same way as videos from channels you're subscribed to.
Like in v1.8.0, extra_channel_handles is an optional parameter, but the program won't start if it is not defined and include_extra_channels is set to True at the same time.
The example section of the ReadMe for this project has also been improved with more examples.