ignore reference assemblies and *.deps.json when building a mod

These aren't useful for mods since they aren't the entry app.

src/SMAPI.ModBuildConfig/Framework/ModFileManager.cs

@@ -164,6 +164,9 @@ namespace StardewModdingAPI.ModBuildConfig.Framework
                 // release zips
                 this.EqualsInvariant(file.Extension, ".zip")
 
+                // unneeded *.deps.json (only SMAPI's top-level one is used)
+                || file.Name.EndsWith(".deps.json")
+
                 // dependencies bundled with SMAPI
                 || IsAssemblyFile("0Harmony")
                 || IsAssemblyFile("Newtonsoft.Json")

src/SMAPI.ModBuildConfig/build/smapi.targets

@@ -15,6 +15,9 @@
     <!-- recognise XNA Framework DLLs in the GAC (only affects mods using new csproj format) -->
     <AssemblySearchPaths>$(AssemblySearchPaths);{GAC}</AssemblySearchPaths>
 
+    <!-- don't create the 'refs' folder (which isn't useful for mods) -->
+    <ProduceReferenceAssembly>false</ProduceReferenceAssembly>
+
     <!-- suppress processor architecture mismatch warning (mods should be compiled in 'Any CPU' so they work in both 32-bit and 64-bit mode) -->
     <ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch>None</ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch>