Add SpatiaLite helpers to CLI (#407)

* Add SpatiaLite CLI helpers
* Add docs for spaitalite helpers
* Fix flake8 issues and add more detail on spatial types
* Run cog and add some help text.
* Use SpatiaLite when calculating coverage, refs #407

Co-authored-by: Simon Willison <swillison@gmail.com>

.github/workflows/test-coverage.yml

@@ -24,6 +24,8 @@ jobs:
         key: ${{ runner.os }}-pip-${{ hashFiles('**/setup.py') }}
         restore-keys: |
           ${{ runner.os }}-pip-
+    - name: Install SpatiaLite
+      run: sudo apt-get install libsqlite3-mod-spatialite
     - name: Install Python dependencies
       run: |
         python -m pip install --upgrade pip