[FIX] Fix submodule clone error in travisCI

Author: mstuttgart

.travis.yml

@@ -3,6 +3,14 @@ language: python
 sudo: required
 dist: trusty
 
+# Handle git submodules yourself
+git:
+    submodules: false
+# Use sed to replace the SSH URL with the public URL, then initialize submodules
+before_install:
+    - sed -i 's/[email protected]:/https:\/\/github.com\//' .gitmodules
+    - git submodule update --init --recursive
+
 before_install:
   - sudo apt-get update
   - sudo apt-get install -y build-essential python3-dev xvfb python3-pyqt5.qtmultimedia