Minor fixes

[xofe]

Another lot of small fixes for things I've noticed. As always, if some aren't wanted just let me know and I'll drop it from the pull request.

• Fix display of subdomains of blocklisted domains (https://github.com/uBlockOrigin/uMatrix-issues/issues/284)
• Call python3 rather than python in build scripts, to allow building without Python 2 installed (the scripts include a python3 shebang line already, so not a major change)
• Open logger/dashboard links adjacent to current tab (I included this in my last lot of fixes, but changes in https://github.com/gorhill/uMatrix/commit/9b29230 undid it)
• Add missing .fa-icon-vflipped CSS, to fix search arrow in asset viewer
• Fix the tooltip of the "obsolete" icon on the assets dashboard page
• Allow line breaks for long domains in the popup panel, so the full domain can be seen (tested on http://www.thelongestdomainnameintheworldandthensomeandthensomemoreandmore.com/): Before: After: