* Mother of all commits:

* Cleaned up copyright notices in AssemblyInfo.cs's
* Added Copyright headers to a bunch of files missing them
* Replaced several common string instances with a static constant to prevent reallocation of the same strings thousands of times. "" -> String.Empty is the first such candidate.

OpenSim/Framework/Servers/BaseHttpServer.cs

@@ -382,7 +382,7 @@ namespace OpenSim.Framework.Servers
 
             Hashtable keysvals = new Hashtable();
             Hashtable headervals = new Hashtable();
-            string host = "";
+            string host = String.Empty;
 
             string[] querystringkeys = request.QueryString.AllKeys;
             string[] rHeaders = request.Headers.AllKeys;