strings: added import dialog partial I8n
RenderGraphDialog: fixed bug that raised an exception when setting the GTK LAF on an empty checkbox
TableImportPlugin: fixed bug that caused a stack overflow because the registering of plugins was placed in the instance constructor instead of in the static constructor/type initializer
StaticUtils: rename LocalizedStore to KeyedStore, since the class does not provide localization proper (though it can be used for that), renamed fields to reflect that