Add JRuby

[headius]

It might be nice to include JRuby, since we appear to be faster than all recent CRuby versions.

On my system (using OpenJDK 11):

[] ~/projects/raytracer/ruby $ rvm ruby-2.7.0 do ruby RayTracer.rb 
Completed in 20886.185999999998 ms

[] ~/projects/raytracer/ruby $ rvm ruby-3.0.2 do ruby RayTracer.rb 
Completed in 16813.604000000003 ms

[] ~/projects/raytracer/ruby $ rvm jruby-9.3.0.0 do ruby RayTracer.rb 
Ignoring executable-hooks-1.6.1 because its extensions are not built. Try: gem pristine executable-hooks --version 1.6.1
Ignoring gem-wrappers-1.4.0 because its extensions are not built. Try: gem pristine gem-wrappers --version 1.4.0
Completed in 13248.208 ms

[] ~/projects/raytracer/ruby $ rvm jruby-9.3.0.0 do ruby -Xcompile.invokedynamic RayTracer.rb 
Ignoring executable-hooks-1.6.1 because its extensions are not built. Try: gem pristine executable-hooks --version 1.6.1
Ignoring gem-wrappers-1.4.0 because its extensions are not built. Try: gem pristine gem-wrappers --version 1.4.0
Completed in 7894.947999999999 ms

If this scales the same way on your end it would put the JRuby results somewhere between HHVM and PHP, which I'd like to see. 😀

[edin]

Hi, I'll try and let you know