Add new PTY node (replaces Pseudoterminal node)

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.

misc/vscode/launch.json

@@ -0,0 +1,33 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "cpp - Build and debug active file",
+            "type": "cppdbg",
+            "request": "launch",
+            "program": "/run/current-system/sw/bin/godot",
+            "args": [],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "externalConsole": false,
+            "MIMode": "gdb",
+            "setupCommands": [
+                {
+                    "description": "Enable pretty-printing for gdb",
+                    "text": "-enable-pretty-printing",
+                    "ignoreFailures": true
+                },
+                //{
+                //    "description": "Debug forked child process",
+                //    "text": "-gdb-set follow-fork-mode child",
+                //}
+            ],
+            "preLaunchTask": "build",
+            "miDebuggerPath": "gdb"
+        }
+    ]
+}

misc/vscode/settings.json

@@ -3,4 +3,21 @@
     "clang-format.executable": "/run/current-system/sw/bin/clang-format",
     "gut-extension.additionalOptions": "-d --no-window",
     "nixEnvSelector.nixShellConfig": "NOT_MODIFIED_ENV",
+    "files.associations": {
+        "array": "cpp",
+        "istream": "cpp",
+        "limits": "cpp",
+        "numeric": "cpp",
+        "sstream": "cpp",
+        "streambuf": "cpp",
+        "utility": "cpp",
+        "optional": "cpp",
+        "ostream": "cpp",
+        "ratio": "cpp",
+        "system_error": "cpp",
+        "functional": "cpp",
+        "tuple": "cpp",
+        "type_traits": "cpp",
+        "*.inc": "cpp"
+    }
 }