Added ubuntu CI and fixed issue uncovered during CI. Also added clang-format

appveyor.yml

@@ -0,0 +1,20 @@
+image:
+  - Visual Studio 2019
+clone_folder: c:\projects\source
+
+environment:
+  Qt5_INSTALL_DIR: 'C:\Qt\5.15.0\msvc2019_64'
+  PATH: '%Qt5_INSTALL_DIR%\bin;%PATH%'
+build_script:
+- cmd: >-
+
+    mkdir build
+
+    cd build
+
+    echo %PATH%
+
+    cmake c:\projects\source -G "Visual Studio 16 2019" -DCMAKE_BUILD_TYPE:STRING=Release
+
+    cmake --build . --config "Release"
+