MonoDevelop does not build anymore with mono trunk because .net 2.0 is not supported anymore

[tpokorra]

https://github.com/mono/ikvm-fork/blob/master/reflect/IKVM.Reflection.csproj references ToolsVersion="3.5", and TargetFrameworkVersion v2.0
this causes an warning when running make on Monodevelop:

[00639] /root/rpmbuild/BUILD/monodevelop-5.8/external/ikvm/reflect/IKVM.Reflection.csproj:  warning : Could not find project file /opt/mono/lib/mono/3.5/Microsoft.CSharp.targets, to import. Ignoring.

and then later an error:

    [00664] Errors:
    [00664] 
    [00664] /root/rpmbuild/BUILD/monodevelop-5.8/Main.sln (default targets) ->
    [00664] (Build target) ->
    [00664] 
    [00664]     /root/rpmbuild/BUILD/monodevelop-5.8/external/ikvm/reflect/IKVM.Reflection.csproj: error : /root/rpmbuild/BUILD/monodevelop-5.8/external/ikvm/reflect/IKVM.Reflection.csproj: /root/rpmbuild/BUILD/monodevelop-5.8/external/ikvm/reflect/IKVM.Reflection.csproj could not import "$(MSBuildToolsPath)\Microsoft.CSharp.targets"