Improve Transpiler speed with async file commands

[zepumph]

Or something else? @jonathanolson and I were brainstorming why every file takes 25ms to transpile. In Transpiler.transpileFunction(), there are mutliple *Sync() calls that may be better as atomic tasks so that we aren't waiting on I/O so much.

[zepumph]

I believe this would be a nice direction, but I'm worried about how async commands would then need to leak into all usages of the transpiler. I won't probably work on this soon.