- Cleaned up disposal in LLamaContext

- sealed some classes not intended to be extended

LLama/LLamaContext.cs

@@ -422,6 +422,8 @@ namespace LLama
         /// <inheritdoc />
         public virtual void Dispose()
         {
+            GC.SuppressFinalize(this);
+
             _ctx.Dispose();
         }
 
@@ -429,12 +431,11 @@ namespace LLama
         /// The state of this model, which can be reloaded later
         /// </summary>
         public class State
-            : SafeHandleZeroOrMinusOneIsInvalid
+            : SafeLLamaHandleBase
         {
             internal State(IntPtr memory)
-                : base(true)
+                : base(memory)
             {
-                SetHandle(memory);
             }
 
             /// <inheritdoc />

LLama/LLamaWeights.cs

@@ -9,7 +9,7 @@ namespace LLama
     /// <summary>
     /// A set of model weights, loaded into memory.
     /// </summary>
-    public class LLamaWeights
+    public sealed class LLamaWeights
         : IDisposable
     {
         private readonly SafeLlamaModelHandle _weights;

LLama/Native/SafeLLamaContextHandle.cs

@@ -8,7 +8,7 @@ namespace LLama.Native
     /// <summary>
     /// A safe wrapper around a llama_context
     /// </summary>
-    public class SafeLLamaContextHandle
+    public sealed class SafeLLamaContextHandle
         : SafeLLamaHandleBase
     {
         #region properties and fields

LLama/Native/SafeLlamaModelHandle.cs

@@ -7,7 +7,7 @@ namespace LLama.Native
     /// <summary>
     /// A reference to a set of llama model weights
     /// </summary>
-    public class SafeLlamaModelHandle
+    public sealed class SafeLlamaModelHandle
         : SafeLLamaHandleBase
     {
         /// <summary>