Added getters and notifications to allow clients of the loaders (DicomStructureSetLoader, OrthancSeriesVolumeProgressiveLoader and OrthancMultiframeVolumeLoader) to know when the loading is finished + added ability for SDL event loop to execute a callback repeatedly (used to check the view loading state)

{
    "extends" : "../../Web/tsconfig-samples",
    "compilerOptions": {
    },
    "include" : [
        "simple-viewer.ts",
        "../../build-wasm/ApplicationCommands_generated.ts"
    ]
}