Merging r6506 through r6510 from branch releases/1.8 to trunk

Note those were mostly backport, so trunk already had most changes.
Also we've not merged all from 1.8 branch, will need another merge (backports tend to cause lots of ugly conflicts, so have to split this a bit)


git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@6515 dfc29bdd-3216-0410-991c-e03cc46cb475

changes.txt

@@ -398,6 +398,7 @@ Changes in 1.9 (not yet released)
 
 --------------------------
 Changes in 1.8.6
+- Backport parts of COpenGLCommon.h to ensure that COpenGLExtensionHandler, COpenGLShaderMaterialRenderer and COpenGLTexture all use identical GL extension settings
 - Backport removing register keywords (deprecated by c++17)
 - Backport bugfix from trunk to make CUserPointerAttribute::setString work on 64-bit systems.
 - Remove unnecessary implemented assignment operator in quaternion, irrMap, SViewFrustum, line2d and IQ3Shader which cause warnings with -Wdeprecated in newer gcc

source/Irrlicht/Irrlicht-gcc.cbp

@@ -835,6 +835,7 @@
 		<Unit filename="COpenGLCoreFeature.h" />
 		<Unit filename="COpenGLCoreRenderTarget.h" />
 		<Unit filename="COpenGLCoreTexture.h" />
+		<Unit filename="COpenGLCommon.h" />
 		<Unit filename="COpenGLDriver.cpp" />
 		<Unit filename="COpenGLDriver.h" />
 		<Unit filename="COpenGLExtensionHandler.cpp" />

source/Irrlicht/Irrlicht10.0.vcxproj

@@ -1151,7 +1151,6 @@
     <ClInclude Include="CZBuffer.h" />
     <ClInclude Include="ITriangleRenderer.h" />
     <ClInclude Include="IZBuffer.h" />
-    <ClInclude Include="resource.h" />
     <ClInclude Include="S2DVertex.h" />
     <ClInclude Include="SB3DStructs.h" />
     <ClInclude Include="CColorConverter.h" />

source/Irrlicht/Irrlicht10.0.vcxproj.filters

@@ -1263,7 +1263,6 @@
     <ClInclude Include="..\..\include\IAnimatedMeshMD3.h">
       <Filter>include\scene</Filter>
     </ClInclude>
-    <ClInclude Include="resource.h" />
     <ClInclude Include="CSceneLoaderIrr.h">
       <Filter>Irrlicht\scene\loaders</Filter>
     </ClInclude>