Fix loading tool in Linux/Mono

src/SHME.ExternalTool.Guts/CollectionExtensions.cs

@@ -1,6 +1,7 @@
 using SHME.ExternalTool.Graphics;
 using System;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace SHME.ExternalTool;
 
@@ -47,4 +48,26 @@ public static int IndexFromKey<TKey, TValue>(this SortedDictionary<TKey, TValue>
 
 		return -1;
 	}
+
+	// These SelectX methods are just a hack to avoid creating anonymous
+	// methods in the main tool assembly whose signatures contain types
+	// defined in an external assembly. PointOfInterest or Trigger, for
+	// example, are defined in SHME.ExternalTool.Guts. Under Mono in
+	// Linux, when BizHawk tries to load the main plugin assembly, Mono
+	// tries to load the types it finds in method signatures, failing on
+	// the aforementioned examples (among others) because the DLLs found
+	// in the ExternalTool attribute's LoadAssemblyFiles array haven't
+	// been loaded yet. This is a bit roundabout, but still effective.
+	public static IEnumerable<TItem2> SelectItem2<TItem1, TItem2>(this IEnumerable<(TItem1, TItem2)> enumerable)
+	{
+		return enumerable.Select((tuple) => tuple.Item2);
+	}
+	public static IEnumerable<TItem2> SelectManyItem2<TItem1, TItem2>(this IEnumerable<(TItem1, IList<TItem2>)> enumerable)
+	{
+		return enumerable.SelectMany((tuple) => tuple.Item2);
+	}
+	public static IEnumerable<(TItem1, TItem2)> SelectTuple<TItem1, TItem2>(this IEnumerable<(TItem1, TItem2)> enumerable)
+	{
+		return enumerable.Select((tuple) => tuple);
+	}
 }

src/SHME.ExternalTool/UI/CustomMainForm.cs

@@ -445,11 +445,10 @@ private void DrawOverlayCommonPre(ref Matrix4x4 matrix, ref Vector3 position, re
 			{
 				Guts.Camera.GetVisibleRenderables(
 					ref Guts.VisibleRenderables, [
-						.. Guts.Pois.Values
-							.Select((tuple) => tuple.Item2),
+						.. Guts.Pois.Values.SelectItem2(),
 						.. Guts.CameraPaths.Values
-							.Select((path) => path)
-							.SelectMany((tuple) => tuple.Item2),
+							.SelectTuple()
+							.SelectManyItem2(),
 						.. Guts.Gems,
 						.. Guts.Lines]);
 			}