Set path to MonoDevelop binaries

MDBinPath is now explicitly set instead of relying on the path
set by the addin maker extension.

Author: mrward

src/MonoDevelop.PowerShell/MonoDevelop.References.proj

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
+    <MDBinDir>..\..\..\monodevelop-7.0\main\build\bin</MDBinDir>
     <MDBinDir Condition=" '$(MDBinDir)' == '' ">..\..\..\..\monodevelop\main\build\bin</MDBinDir>
   </PropertyGroup>
   <ItemGroup>