Change project structure;

Added new c# binding;

native/external/assimp/ai_assert.h

@@ -0,0 +1,74 @@
+/*
+---------------------------------------------------------------------------
+Open Asset Import Library (assimp)
+---------------------------------------------------------------------------
+
+Copyright (c) 2006-2025, assimp team
+
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms,
+with or without modification, are permitted provided that the following
+conditions are met:
+
+* Redistributions of source code must retain the above
+  copyright notice, this list of conditions and the
+  following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+  copyright notice, this list of conditions and the
+  following disclaimer in the documentation and/or other
+  materials provided with the distribution.
+
+* Neither the name of the assimp team, nor the names of its
+  contributors may be used to endorse or promote products
+  derived from this software without specific prior
+  written permission of the assimp team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+---------------------------------------------------------------------------
+*/
+
+/** @file ai_assert.h
+ *  @brief Declares the assimp-specific assertion handler.
+ */
+
+#pragma once
+#ifndef AI_ASSERT_H_INC
+#define AI_ASSERT_H_INC
+
+#include <assimp/defs.h>
+
+#if defined(ASSIMP_BUILD_DEBUG)
+
+namespace Assimp {
+
+/// @brief Assert violation behavior can be customized: see AssertHandler.h.
+/// @param failedExpression     The expression to validate.
+/// @param file                 The file location
+/// @param line                 The line number
+ASSIMP_API void aiAssertViolation(const char* failedExpression, const char* file, int line);
+
+}
+#endif
+
+// Define assertion resolinig
+#if defined(ASSIMP_BUILD_DEBUG)
+#   define ai_assert(expression) (void)((!!(expression)) || (Assimp::aiAssertViolation(#expression, __FILE__, __LINE__), 0))
+#   define ai_assert_entry() ai_assert(false)
+#else
+#   define  ai_assert(expression)
+#   define  ai_assert_entry()
+#endif // ASSIMP_BUILD_DEBUG
+
+#endif // AI_ASSERT_H_INC