Add "warnings as errors" support for nant and monodevelop to Prebuild (though monodevelop may ignore this).

Prebuild/src/Core/Targets/MonoDevelopTarget.cs

@@ -245,7 +245,7 @@ namespace Prebuild.Core.Targets
 					ss.WriteLine(" />");
 					
 					ss.Write("      <Execution");
-					ss.Write(" runwithwarnings=\"True\"");
+					ss.Write(" runwithwarnings=\"{0}\"", !conf.Options.WarningsAsErrors);
 					ss.Write(" consolepause=\"True\"");
 					ss.Write(" runtime=\"{0}\"", netRuntime);
                     ss.Write(" clr-version=\"Net_2_0\"");

Prebuild/src/Core/Targets/NAntTarget.cs

@@ -283,6 +283,11 @@ namespace Prebuild.Core.Targets
                     break;
                 }
                 foreach (ConfigurationNode conf in project.Configurations)
+                {
+                    ss.Write(" warnaserror=\"{0}\"", conf.Options.WarningsAsErrors);
+                    break;
+                }
+                foreach (ConfigurationNode conf in project.Configurations)
                 {
                     ss.Write(" define=\"{0}\"", conf.Options.CompilerDefines);
                     break;