add liner for up-arrow command history

[Jason E. Aten, Ph.D.]

github.com/glycerine/liner provides command line history upon up-arrow, tab-complete, etc.

example use:

https://github.com/glycerine/zygomys/blob/master/zygo/liner.go

https://github.com/glycerine/zygomys/blob/master/zygo/repl.go

A small task, good first issue, would be to integrate liner.go with gi/luajit.go

[Jason E. Aten, Ph.D.]

done as of v0.8.0