Performance improvements for OMLZip.

[NicolasRouquette]

In OMLSpecificationTables loadOMLZipResource should not call includeModulesince it will be called, if needed, later in processQueue.

Test whether void resolve(ResourceSet rs, OMLZipResource r) has become superfluous and if so remove it.

[NicolasRouquette]

With the profiler, a significant performance bottleneck comes from Xtext's linking, which in OML, is defined in gov.nasa.jpl.imce.oml.linking.OMLLinkingService.getLinkedObjects.

When converting thousands of OML models in *.oml textual concrete syntax, there can be hundreds of thousands of calls to OMLLinkingService.getLinkedObjects even after all models have been loaded. This is clearly an opportunity for a read-only cache optimization.