Nxstart

- Added the `libt` command for creating a `libtransistor` project
- Added `libtransistor` template
- Added `.gitignore` to the BrewJS and PyNX templates
- Added more tests
- Updated both README files

- Added `pynx` command for creating a PyNX project
- Changed the `cpp` and `js` commands to `libnx` and `brewjs`, so they better reflect their library

Added `pytest` tests for the `cpp` and `js` commands.
Also added a `.gitignore` file to the `js` template.

You can now create a BrewJS project by running `nxstart js` in a terminal.

This version now uses `os.path.dirname` to fetch the project directory, as `distutils.dirname` doesn't work on some machines.