Use SIMD where possible?

SIMD instructions are going to be available in ECMAScript 7, and are already supported in Firefox and Crosswalk. Plus, there's a Typed Arrays based polyfill available at https://github.com/johnmccutchan/ecmascript_simd. For projects using convnetjs, especially on mobile, SIMD might make everything a bit faster.

No file, test, or entry point is named. Start by locating convnetjs's numerical computation paths and reviewing the linked ECMAScript SIMD polyfill, then determine where SIMD could apply and how mobile performance would be measured. Done should include a defined scope and evidence that the affected computations are faster.

Written by the indexing model from the issue text.