Added basic metric view functionality

org.fortiss.tooling.ext.quality.ui/META-INF/MANIFEST.MF

org.fortiss.tooling.ext.quality.ui/build.properties

...fortiss/tooling/ext/quality/ui/view/fx/MetricsViewFx.fxml

...s/tooling/ext/quality/ui/view/fx/MetricsFXController.java

...iss/tooling/ext/quality/ui/view/fx/MetricsFXViewPart.java

org.fortiss.tooling.ext.quality/build.properties

...iss.tooling.ext.quality/html/developer/documentation.html

org.fortiss.tooling.ext.quality/plugin.xml

...ng/ext/quality/service/HierarchicElementSizeProvider.java

...ss/tooling/ext/quality/service/IModelQualityProvider.java

...tiss/tooling/ext/quality/service/ModelQualityService.java