.async() doesn't honor future(thisArg)

[tcf909]

When using .async() to turn a sync function in to an async one, the return function from .async() does not allow a this arg to be applied, because the cxt variable is always used.

"cxt = cxt || this;"

needs to be added right below:

"var args = arguments, cb = args[args.length-1];"

in syncho.js (at line 34)

This allows future() to set a thisArg when using .async() without .async(cxt).