message: Add gltfpack to Travis-CI
  This will make sure we don't regress on any platform in the future.
diff: @@ -22,7 +22,8 @@ script:
  - if [[ "$TRAVIS_COMPILER" == "clang" ]]; then make config=sanitize test; fi
  - if [[ "$TRAVIS_OS_NAME" != "windows" ]]; then make config=debug test; fi
  - if [[ "$TRAVIS_OS_NAME" != "windows" ]]; then make config=release test; fi
  - - if [[ "$TRAVIS_OS_NAME" == "windows" ]]; then cmake -G "$TARGET" -DBUILD_DEMO=ON; fi
  + - if [[ "$TRAVIS_OS_NAME" != "windows" ]]; then make config=release gltfpack; fi
  + - if [[ "$TRAVIS_OS_NAME" == "windows" ]]; then cmake -G "$TARGET" -DBUILD_DEMO=ON -DBUILD_TOOLS=ON; fi
  - if [[ "$TRAVIS_OS_NAME" == "windows" ]]; then cmake --build . -- -property:Configuration=Debug -verbosity:minimal; fi
  - if [[ "$TRAVIS_OS_NAME" == "windows" ]]; then ./Debug/demo.exe demo/pirate.obj; fi
  - if [[ "$TRAVIS_OS_NAME" == "windows" ]]; then cmake --build . -- -property:Configuration=Release -verbosity:minimal; fi
  