goawk

Eliminate numChecked and a couple of other speedups / simplifications.

A couple of performance improvements related to value handling and numeric strings.

Added support for calling native Go functions from AWK. See documentation of the Funcs field here: https://godoc.org/github.com/benhoyt/goawk/interp#Config

Ensure printf has one or more args at parse time. Add some unit tests to get more coverage.

Initial working and tested version! Read more: https://benhoyt.com/writings/goawk/