Added infrastructure to remove references by specified modules only.

Author: MDoerner

Rubberduck.Parsing/Symbols/Declaration.cs

@@ -616,5 +616,12 @@ public void ClearReferences()
         {
             _references = new ConcurrentBag<IdentifierReference>();
         }
+
+        public void RemoveReferencesFrom(ICollection<QualifiedModuleName> modulesByWhichToRemoveReferences)
+        {
+            //This gets replaced with a new ConcurrentBag because one cannot remove specific items from a ConcurrentBag.
+            //Moreover, changing to a ConcurrentDictionary<IdentifierReference,byte> breaks all sorts of tests, for some obscure reason. 
+            var newReferences = new ConcurrentBag<IdentifierReference>(_references.Where(reference => !modulesByWhichToRemoveReferences.Contains(reference.QualifiedModuleName)));
+        }
     }
 }

Rubberduck.Parsing/VBA/RubberduckParserState.cs

@@ -795,6 +795,14 @@ public void ClearAllReferences()
             }
         }
 
+        public void RemoveAllReferencesBy(ICollection<QualifiedModuleName> referencesFromToRemove)
+        {
+            foreach (var declaration in AllDeclarations)
+            {
+                declaration.RemoveReferencesFrom(referencesFromToRemove);
+            }
+        }
+
         public bool ClearStateCache(IVBComponent component, bool notifyStateChanged = false)
         {
             return component != null && ClearStateCache(new QualifiedModuleName(component), notifyStateChanged);