Improve download robustness

Test and verify changes made to fix recent downloading issues (#6, #8 & #10) are in order. Thanks especially to @spcified for his pull requests!

Support for new Bandcamp CDN

• Fix #6 crashing the application on track downloads due to new CDN and data format

Version 1.47

• Possibly fix #5 by handling streams prematurely ending.
• Added a new CLI flag --no-missing that allows aborting album downloads if a track on it is unreleased or unavailable
• ID3 and artwork CLI flags would not propagate on discography downloads
• Discography downloads now follow links to possible further sub Bandcamp pages
• Track & album matching now allows for more patterns and flexibility including regex specifications
• Improve confidence checks when comparing local and remote files
• Removed some unused parts of the code that were deprecated when switching off of ranged streams