Adding cross-platform binary compilation support, as well as Travis CI tests.

- Added initial .travis.yml for all three platforms
- Applied a simple fix to ProperTree.command for pyinstaller failing to load/bundle all dependencies

Author: Dids

.travis.yml

@@ -0,0 +1,26 @@
+# https://docs.travis-ci.com/user/languages/python/
+language: python
+matrix:
+  include:
+    - name: "Python 3.7 on Linux"
+      python: 3.7
+      dist: xenial
+    - name: "Python 3.7 on macOS"
+      os: osx
+      osx_image: xcode10.2
+      language: shell
+    - name: "Python 3.7 on Windows"
+      os: windows
+      language: shell
+      before_install: choco install python
+      env: PATH=/c/Python37:/c/Python37/Scripts:$PATH
+install:
+  - pip3 install pyinstaller
+script:
+  - pyinstaller \
+      --clean \
+      --windowed \
+      --onedir \
+      --onefile \
+      --add-data Scripts:Scripts \
+      ProperTree.command

ProperTree.command

@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 import sys, os, binascii, base64
+import queue, json, ctypes # Fix for pyinstaller failing to bundle dependencies
 try:
     import Tkinter as tk
     import ttk