Add howl_async spec helper
ljglibs: Add missing jit.off, fix read_async with count == 0
log: remove any location info before propagating to status bar

Since it easily becomes unwieldy.
Add InputStream.read_all

Also add spec, and fix missing propagation of num parameter.
Add Process.execute(..)

For easily running a command and capturing output. For those
cases where it's not important to act on any output right away.