In order to use the gdnative library as an editor plugin it was
neccessary to set the `reloadable` property of the gdnlib file to false,
in order to prevent crashes when the godot editor window lost focus.
This may have consequences when recompiling the library.
See: https://docs.godotengine.org/en/3.3/classes/class_gdnativelibrary.html#class-gdnativelibrary-property-reloadable
Still crashes quite frequently and doesn't close child processes
properly.
Part of #43.
Uses fork of node-pty native code for forking pseudoterminals.
Uses libuv pipe handle to communicate with the child process.
- Paves the way for cross-platform (Linux, macOS and Windows) support.
- Renames Pseudoterminal to PTY (which is much easier to type and spell :D).
- Better performance than the old Pseudoterminal node. Especially when
streaming large amounts of data such as running the `yes` command.
- Allows setting custom file, args, initial window size, cwd, env vars
(including important ones such as TERM and COLORTERM) and uid/gid
on Linux and macOS.
- Returns process exit code and terminating signal.
