List info for connected Magewell USB devices and nosignal tool polishing PR

[vmdocua]

PR to provide additional information about connected Magewell USB capture devices. Closes #94.
Also closes small tasks like:

#82:

• nosignal-batch script to check directory with videos (mkv).
• nosignal tool extended with fixup option for truncated and invalid duration videos.
• nosignal algorithm changed to another one (based on reference nosignal image), because original one looking for rainbow produced false-positive results.