TenFourFox FPR5 available

TenFourFox Feature Parity Release 5 final is available for testing (downloads, hashes, release notes). There are no other changes other than the relevant security updates and the timer resolution reduction for anti-Spectre hardening. Assuming no major issues, it will become live on Monday evening Pacific time.

For FPR6, there will be some bug fixes and optimizations, and I'm also looking at the feasibility of basic CSS Grid support, requestIdleCallback() (using our Mach factor code to improve system utilization), date-time pickers and some JavaScript speedups. Also, I'd like to welcome fresh meat new contributors Ken and Raphael who have submitted fixes for compiling TenFourFox with gcc 4.8.5 and are working with me on support for gcc 6.4.0, where we currently have a startup crash if optimization is enabled. If you're interested in helping us investigate, see issue 464.