Add --script-mode / -s and fix --dir as well as add tests

[bradennapier]

ts-node team is discussing making --script-mode a default setting in the near future. Also, since the --dir option was configured incorrectly, ts-node-dev had some cases that were impossible to make work properly. This PR adds the following:

• support for --script-mode and -s from ts-node
  • uses the same logic used by ts-node to handle the arguments here
• support for --dir which currently is seutp as a boolean rather than a string so it doesn't work properly
• tests for all cases provided including error cases.

It is easy to install since there is no compilation for this project - yarn add --dev git://github.com/bradennapier/ts-node-dev.git#feature/script-mode" should work if you want to use this before it is published. Hopefully since it is quite critical in many cases it will get merged quickly :-)

[wclr]

Ok I believe this should work) Thanks!

[bradennapier]

No problem, thanks for the quick response!