Updated README example to use OOP api (#168)

Author: adamdusty

README.md

@@ -64,7 +64,7 @@ The tutorials have been tested to run on Windows and Linux, however the build (u
 ```csharp
     using System;
     using System.Runtime.InteropServices;
-    using LLVMSharp;
+    using LLVMSharp.Interop;
 
     internal sealed class Program
     {
@@ -73,21 +73,20 @@ The tutorials have been tested to run on Windows and Linux, however the build (u
 
         private static void Main(string[] args)
         {
-            LLVMBool Success = new LLVMBool(0);
-            LLVMModuleRef mod = LLVM.ModuleCreateWithName("LLVMSharpIntro");
+            LLVMModuleRef mod = LLVMModuleRef.CreateWithName("LLVMSharpIntro");
 
-            LLVMTypeRef[] param_types = { LLVM.Int32Type(), LLVM.Int32Type() };
-            LLVMTypeRef ret_type = LLVM.FunctionType(LLVM.Int32Type(), param_types, false);
-            LLVMValueRef sum = LLVM.AddFunction(mod, "sum", ret_type);
+            LLVMTypeRef[] param_types = new LLVMTypeRef[2] { LLVMTypeRef.Int32, LLVMTypeRef.Int32 };
+            LLVMTypeRef ret_type = LLVMTypeRef.CreateFunction(LLVMTypeRef.Int32, param_types);
+            LLVMValueRef sum = mod.AddFunction("sum", ret_type);
 
-            LLVMBasicBlockRef entry = LLVM.AppendBasicBlock(sum, "entry");
+            LLVMBasicBlockRef entry = sum.AppendBasicBlock("entry");
 
-            LLVMBuilderRef builder = LLVM.CreateBuilder();
-            LLVM.PositionBuilderAtEnd(builder, entry);
-            LLVMValueRef tmp = LLVM.BuildAdd(builder, LLVM.GetParam(sum, 0), LLVM.GetParam(sum, 1), "tmp");
-            LLVM.BuildRet(builder, tmp);
+            LLVMBuilderRef builder = LLVMBuilderRef.Create(mod.Context);
+            builder.PositionAtEnd(entry);
+            LLVMValueRef tmp = builder.BuildAdd(sum.Params[0], sum.Params[1], "tmp");
+            builder.BuildRet(tmp);
 
-            if (LLVM.VerifyModule(mod, LLVMVerifierFailureAction.LLVMPrintMessageAction, out var error) != Success)
+            if (!mod.TryVerify(LLVMVerifierFailureAction.LLVMPrintMessageAction, out var error))
             {
                 Console.WriteLine($"Error: {error}");
             }
@@ -101,26 +100,24 @@ The tutorials have been tested to run on Windows and Linux, however the build (u
             LLVM.InitializeX86AsmPrinter();
 
             LLVMMCJITCompilerOptions options = new LLVMMCJITCompilerOptions { NoFramePointerElim = 1 };
-            LLVM.InitializeMCJITCompilerOptions(options);
-            if (LLVM.CreateMCJITCompilerForModule(out var engine, mod, options, out error) != Success)
+            if (!mod.TryCreateMCJITCompiler(out var engine, ref options, out error))
             {
                 Console.WriteLine($"Error: {error}");
             }
 
-            var addMethod = (Add)Marshal.GetDelegateForFunctionPointer(LLVM.GetPointerToGlobal(engine, sum), typeof(Add));
+            var addMethod = (Add)Marshal.GetDelegateForFunctionPointer(engine.GetPointerToGlobal(sum), typeof(Add));
             int result = addMethod(10, 10);
 
             Console.WriteLine("Result of sum is: " + result);
 
-            if (LLVM.WriteBitcodeToFile(mod, "sum.bc") != 0)
+            if (mod.WriteBitcodeToFile("sum.bc") != 0)
             {
                 Console.WriteLine("error writing bitcode to file, skipping");
             }
 
-            LLVM.DumpModule(mod);
-
-            LLVM.DisposeBuilder(builder);
-            LLVM.DisposeExecutionEngine(engine);
+            mod.Dump();
+            builder.Dispose();
+            engine.Dispose();
         }
     }
 ````