Load new DLL first so existing projects don't see odd behavior

As introduced in #698, the engine now compiles to `ProjectName DLL.dll` instead of `ProjectName.dll`. If you have an existing project and merge these changes in, then recompile, you'll end up with both files adjacent to your executable. The engine currently looks for `ProjectName.dll` first, and if it finds it, loads it. This change reverses that order, so the new-format DLL is loaded in preference to the old one - but you can still use a filename without the ` DLL` suffix when deploying, if you prefer.