Client-side JS with Nim

[Araq]

As long as the size is reasonable (for the initial download), say under 1MB, 
"Size of the produced JS file" is a meaningless number. You cannot guess the 
really interesting numbers like the size of the produced machine code from the 
JIT, the memory consumption, the latency, the throughput from the size of the 
produced JS file. You might as well measure the length of your fingernails 
instead, it's as meaningful.