Add minor tweaks for debug code and add mono dev docs

Development/Documentation/mono.md

@@ -0,0 +1,13 @@
+## Mono
+
+Custom fork: [https://github.com/FlaxEngine/mono](https://github.com/FlaxEngine/mono) with custom features for C# assemblies hot-reloading at runtime without domain unload (more: [https://flaxengine.com/blog/flax-facts-16-scripts-hot-reload/](https://flaxengine.com/blog/flax-facts-16-scripts-hot-reload/)).
+
+### Notes
+
+Some useful notes and tips for devs:
+* When working with mono fork set `localRepoPath` to local repo location in `Source\Tools\Flax.Build\Deps\Dependencies\mono.cs`
+* To update mono deps when developing/updating use `.\Development\Scripts\Windows\CallBuildTool.bat -log -ReBuildDeps -verbose -depsToBuild=mono -platform=Windows`, then build engine and run it
+* `MONO_GC_DEBUG=check-remset-consistency` - it will do additional checks at each collection to see if there are any missing write barriers
+* `MONO_GC_DEBUG=nursery-canaries` - it might catch some buffer overflows in case of problems in code.
+* Methods `mono_custom_attrs_from_property` and `mono_custom_attrs_get_attr` are internally cached
+* If C++ mono call a method in c# that will throw an error, error will be handled but, not completly. Calling relase domain will return random `Access memory violation`. First search for error in c# code. No workaround yet.

Source/Engine/Scripting/ManagedCLR/MCore.Mono.cpp

@@ -115,6 +115,8 @@ void* MonoCalloc(size_t count, size_t size)
 
 #if USE_MONO_PROFILER
 
+#include "Engine/Core/Types/StringBuilder.h"
+
 struct FlaxMonoProfiler
 {
 };
@@ -123,7 +125,7 @@ FlaxMonoProfiler Profiler;
 
 struct StackWalkDataResult
 {
-    StringAnsi Buffer;
+    StringBuilder Buffer;
 };
 
 mono_bool OnStackWalk(MonoMethod* method, int32_t native_offset, int32_t il_offset, mono_bool managed, void* data)
@@ -135,16 +137,16 @@ mono_bool OnStackWalk(MonoMethod* method, int32_t native_offset, int32_t il_offs
         auto mName = mono_method_get_name(method);
         auto mKlassNameSpace = mono_class_get_namespace(mono_method_get_class(method));
         auto mKlassName = mono_class_get_name(mono_method_get_class(method));
-        result->Buffer += mKlassNameSpace;
+        result->Buffer.Append(mKlassNameSpace);
-        result->Buffer += ".";
+        result->Buffer.Append(TEXT("."));
-        result->Buffer += mKlassName;
+        result->Buffer.Append(mKlassName);
-        result->Buffer += "::";
+        result->Buffer.Append(TEXT("::"));
-        result->Buffer += mName;
+        result->Buffer.Append(mName);
-        result->Buffer += "\n";
+        result->Buffer.Append(TEXT("\n"));
     }
     else if (!managed)
     {
-        result->Buffer += "<unmanaged>\n";
+        result->Buffer.Append(TEXT("<unmanaged>\n"));
     }
 
     return 0;
@@ -167,10 +169,10 @@ void OnGCAllocation(MonoProfiler* profiler, MonoObject* obj)
 		if (details)
 		{
 			StackWalkDataResult stackTrace;
-			stackTrace.Buffer.reserve(1024);
+			stackTrace.Buffer.SetCapacity(1024);
 			mono_stack_walk(&OnStackWalk, &stackTrace);
 
-			LOG(Info, "GC new: {0}.{1} ({2} bytes). Stack Trace:\n{3}", name_space, name, size, stackTrace.Buffer.c_str());
+			LOG(Info, "GC new: {0}.{1} ({2} bytes). Stack Trace:\n{3}", String(name_space), String(name), size, stackTrace.Buffer.ToStringView());
 		}
 	}
 #endif