Let MonoDevelop 4.0 re-arrange the .sln and .csproj files

This is just the result of opening the solution properties without
changing anything, to let MonoDevelop 4.0 re-arrange the .sln and
.csproj as it wants. This should remove noise in later commits that
contain real changes.
Switch csproj files to Mono/.NET 4.0 target framework

This also upgrades the solution file to the Visual Studio 2010 format.
Hyena.csproj: Don't require specific version of nunit.framework
Hyena.sln: Adjust naming convention policy to match our guidelines

Only real adjustment is to have lower case parameter names, the rest is
default values as set by MonoDevelop.