Fixes: Web links in Help menu and Blender menu take over 10 seconds to open the webpage from the instant of clicking.
If Blender and the default browser (Safari or Firefox) are on different spaces/ desktops, browser takes focus, but shows spinning wheel, and then a ~5 delay before populating the address bar.

Uses webbrowser.open_new_tab(url) instead of webbrowser.open(url).

https://docs.python.org/3.7/library/webbrowser.html#webbrowser.open
https://docs.python.org/3.7/library/webbrowser.html#webbrowser.open_new_tab