Urlscan

* User-option -W --whitespace-off: remove blank lines and ellipses
* Update documentation for feature --whitespace-off
* Correct regex example in urlscan.1
* Sort and align docstrings
* Merge branch 'palette' into develop
* Fix for https://github.com/firecat53/urlscan/issues/115
* Revert "Hopefully fix 105. Escapes every "&" in the URL". Fixes 107
* Update packaging and setup to current best practices

* Python 3.6+ required
* Convert to newer email.message.EmailMessage format for processing. Closes 98
* Hopefully fix 105. Escapes every "&" in the URL
* Attempt --run-safe implementation
* Fixes 106
* Scan a selection of email headers for URLs. Closes 97.
* Add option for custom regex. Closes 79.
* Allow $ as an acceptable trailing character
* Fix urwid reverse error. Thanks to pavoljuhas. Closes 99

* Change shebang to specifically call python3
* Add --width flag to change displayed width. Closes 92.
* Update tlds and copyright dates
* Remove workaround for fixed python webbrowser bug (94)
* Add -R option to reverse URL/context output. Closes 90
* Add --single option to quit after opening/copying first link. Closes 95
* Support wl-clipboard. Resolve 88.

* Remove Python 2 compatibility

* Cycle through opening links with webbrowser module, xdg-open or --run argument
* Add option to copy to primary selection or clipboard. Fix 87
* Generate new config file using command line switch instead of keybinding
* Allow remapping a key to open url in addition to space and enter
* Show help menu with F1 and show dynamic keybindings
* Allow editing key bindings in config.json. Fix 72.

* Add shortcut to copy URL to clipboard (primary).
* Add option to pipe URL into external command.