feat: use libexiv2 to obtain more image metadata

.github/workflows/ubuntu.yml

@@ -10,7 +10,7 @@ jobs:
     steps:
     - uses: actions/checkout@v1
     - name: Get build dept.
-      run: sudo apt install cmake qtbase5-dev libqt5svg5-dev qttools5-dev
+      run: sudo apt install cmake extra-cmake-modules qtbase5-dev libqt5svg5-dev qttools5-dev libexiv2-dev
     - name: Build it
       run: |
         mkdir build