Feature/codegen (#1480)

* Add the ability to automatically generate code to extract values out of a Dictionary (see https://github.com/openspace/codegen for more information on how to use this)
* Applied this technique to a large number of cases in the codebase
* Don't add _codegen files to the repository

Co-authored-by: Emma Broman <emma.broman@liu.se>

modules/base/rendering/renderableplaneimageonline.cpp

@@ -41,24 +41,20 @@ namespace {
         "this value is changed, the image at the new path will automatically be loaded "
         "and displayed."
     };
+
+    struct [[codegen::Dictionary(RenderablePlaneImageOnline)]] Parameters {
+        // [[codegen::verbatim(TextureInfo.description)]]
+        std::string url [[codegen::key("URL")]];
+    };
+#include "renderableplaneimageonline_codegen.cpp"
 } // namespace
 
 namespace openspace {
 
 documentation::Documentation RenderablePlaneImageOnline::Documentation() {
-    using namespace documentation;
-    return {
-        "Renderable Plane Image Online",
-        "base_renderable_plane_image_online",
-        {
-            {
-                TextureInfo.identifier,
-                new StringVerifier,
-                Optional::No,
-                TextureInfo.description,
-            }
-        }
-    };
+    documentation::Documentation doc = codegen::doc<Parameters>();
+    doc.id = "base_renderable_plane_image_online";
+    return doc;
 }
 
 RenderablePlaneImageOnline::RenderablePlaneImageOnline(
@@ -66,20 +62,12 @@ RenderablePlaneImageOnline::RenderablePlaneImageOnline(
     : RenderablePlane(dictionary)
     , _texturePath(TextureInfo)
 {
-    documentation::testSpecificationAndThrow(
-        Documentation(),
-        dictionary,
-        "RenderablePlaneImageOnline"
-    );
+    const Parameters p = codegen::bake<Parameters>(dictionary);
 
     _texturePath.onChange([this]() { _textureIsDirty = true; });
     addProperty(_texturePath);
 
-    std::string texturePath;
-    if (dictionary.hasKey(TextureInfo.identifier)) {
-        _texturePath = dictionary.value<std::string>(TextureInfo.identifier);
-    }
-
+    _texturePath = p.url;
     addProperty(_texturePath);
 }