Add configurable path to script engine assemblies

Adding ability to place script engine assemblies outside
	the codebase directories.

	Uses new [XEngine] option: ScriptEnginesPath = "path_to_assemblies"

Signed-off-by: Melanie <melanie@t-data.com>

OpenSim/Region/ScriptEngine/Interfaces/IScriptEngine.cs

@@ -82,6 +82,7 @@ namespace OpenSim.Region.ScriptEngine.Interfaces
         IConfig Config { get; }
         IConfigSource ConfigSource { get; }
         string ScriptEngineName { get; }
+        string ScriptEnginePath { get; }
         IScriptApi GetApi(UUID itemID, string name);
     }
 }