imageconverter,sceneconverter: support option subgroups as well.

src/Magnum/Trade/Implementation/converterUtilities.h

@@ -46,20 +46,34 @@ void setOptions(PluginManager::AbstractPlugin& plugin, const std::string& option
         Utility::String::trimInPlace(keyValue[0]);
         Utility::String::trimInPlace(keyValue[2]);
 
+        std::vector<std::string> keyParts = Utility::String::split(keyValue[0], '/');
+        CORRADE_INTERNAL_ASSERT(!keyParts.empty());
+        Utility::ConfigurationGroup* group = &plugin.configuration();
+        bool groupNotRecognized = false;
+        for(std::size_t i = 0; i != keyParts.size() - 1; ++i) {
+            Utility::ConfigurationGroup* subgroup = group->group(keyParts[i]);
+            if(!subgroup) {
+                groupNotRecognized = true;
+                subgroup = group->addGroup(keyParts[i]);
+            }
+            group = subgroup;
+        }
+
         /* Provide a warning message in case the plugin doesn't define given
            option in its default config. The plugin is not *required* to have
            those tho (could be backward compatibility entries, for example), so
            not an error. */
-        if(!plugin.configuration().valueCount(keyValue[0]))
+        if(groupNotRecognized || !group->hasValue(keyParts.back())) {
             Warning{} << "Option" << keyValue[0] << "not recognized by" << plugin.plugin();
+        }
 
         /* If the option doesn't have an =, treat it as a boolean flag that's
            set to true. While there's no similar way to do an inverse, it's
            still nicer than causing a fatal error with those. */
         if(keyValue[1].empty())
-            plugin.configuration().setValue(keyValue[0], true);
+            group->setValue(keyParts.back(), true);
         else
-            plugin.configuration().setValue(keyValue[0], keyValue[2]);
+            group->setValue(keyParts.back(), keyValue[2]);
     }
 }
 

src/Magnum/Trade/imageconverter.cpp

@@ -97,7 +97,8 @@ need to be specified.
 The `-i` / `--importer-options` and `-c` / `--converter-options` arguments
 accept a comma-separated list of key/value pairs to set in the importer /
 converter plugin configuration. If the `=` character is omitted, it's
-equivalent to saying `key=true`.
+equivalent to saying `key=true`; configuration subgroups are delimited with
+`/`.
 
 @section magnum-imageconverter-example Example usage
 
@@ -165,7 +166,7 @@ be specified.
 The -i / --importer-options and -c / --converter-options arguments accept a
 comma-separated list of key/value pairs to set in the importer / converter
 plugin configuration. If the = character is omitted, it's equivalent to saying
-key=true.)")
+key=true; configuration subgroups are delimited with /.)")
         .parse(argc, argv);
 
     PluginManager::Manager<Trade::AbstractImporter> importerManager{

src/Magnum/Trade/sceneconverter.cpp

@@ -90,7 +90,8 @@ and images present in the file. **This option is currently mandatory.**
 The `-i` / `--importer-options` and `-c` / `--converter-options` arguments
 accept a comma-separated list of key/value pairs to set in the importer /
 converter plugin configuration. If the `=` character is omitted, it's
-equivalent to saying `key=true`.
+equivalent to saying `key=true`; configuration subgroups are delimited with
+`/`.
 
 @see @ref magnum-imageconverter
 */
@@ -162,7 +163,7 @@ images present in the file.
 The -i / --importer-options and -c / --converter-options arguments accept a
 comma-separated list of key/value pairs to set in the importer / converter
 plugin configuration. If the = character is omitted, it's equivalent to saying
-key=true.)")
+key=true; configuration subgroups are delimited with /.)")
         .parse(argc, argv);
 
     /* Load importer plugin, or use the blob shim in case the extension