Replaced NV_half_float with hopefully more standard ARB_half_float.

According to reports on delphigl.de this extension is far more supported
in comparison to the NV version (and also there's much less FF cruft in
the specification).

doc/opengl-support.dox

@@ -49,7 +49,6 @@ following:
 
 @todo @extension{EXT,texture_array} overlaps with @extension{ARB,framebuffer_object}
 @todo Add @extension{ARB,depth_buffer_float} and implement the missing @fn_gl{DepthRange} function, but keep (and implement) @extension{NV,depth_buffer_float} for non-linear depth buffer
-@todo @extension{ARB,half_float_pixel}, @extension{ARB,half_float_vertex}?
 
 %Extension                                  | Status
 ------------------------------------------- | ------
@@ -62,6 +61,7 @@ GLSL 1.30                                   | done
 @extension{ARB,texture_rg}                  | done
 @extension{ARB,vertex_array_object}         | done
 @extension{ARB,framebuffer_object}          | done
+@extension{ARB,half_float_vertex}           | done
 @extension{EXT,gpu_shader4}                 | done
 @extension{EXT,packed_float}                | done
 @extension{EXT,texture_array}               | done
@@ -71,7 +71,6 @@ GLSL 1.30                                   | done
 @extension{EXT,draw_buffers2}               | |
 @extension{EXT,texture_integer}             | done (GL 3.0 subset)
 @extension{EXT,transform_feedback}          | |
-@extension{NV,half_float}                   | done (GL 3.0 subset)
 @extension{NV,depth_buffer_float}           | |
 @extension{NV,conditional_render}           | done
 

src/Magnum/AbstractShaderProgram.h

@@ -1137,7 +1137,7 @@ template<UnsignedInt location, class T> class AbstractShaderProgram::Attribute {
 
             /**
              * Half float. Only for float attribute types.
-             * @requires_gl30 %Extension @extension{NV,half_float}
+             * @requires_gl30 %Extension @extension{ARB,half_float_vertex}
              * @requires_gles30 %Extension @es_extension{OES,vertex_half_float}
              *      in OpenGL ES 2.0
              */

src/Magnum/ColorFormat.h

@@ -331,7 +331,7 @@ enum class ColorType: GLenum {
 
     /**
      * Each component half float.
-     * @requires_gl30 %Extension @extension{NV,half_float} / @extension{ARB,half_float_pixel}
+     * @requires_gl30 %Extension @extension{ARB,half_float_pixel}
      * @requires_gles30 For texture data only, extension
      *      @es_extension2{OES,texture_half_float,OES_texture_float} in OpenGL
      *      ES 2.0

src/Magnum/Context.cpp

@@ -80,6 +80,7 @@ const std::vector<Extension>& Extension::extensions(Version version) {
         _extension(GL,ARB,texture_rg),
         _extension(GL,ARB,vertex_array_object),
         _extension(GL,ARB,framebuffer_object),
+        _extension(GL,ARB,half_float_vertex),
         _extension(GL,EXT,gpu_shader4),
         _extension(GL,EXT,packed_float),
         _extension(GL,EXT,texture_array),
@@ -89,7 +90,6 @@ const std::vector<Extension>& Extension::extensions(Version version) {
         _extension(GL,EXT,draw_buffers2),
         _extension(GL,EXT,texture_integer),
         _extension(GL,EXT,transform_feedback),
-        _extension(GL,NV,half_float),
         _extension(GL,NV,depth_buffer_float),
         _extension(GL,NV,conditional_render)};
     static const std::vector<Extension> extensions310{

src/Magnum/Extensions.h

@@ -82,6 +82,7 @@ namespace GL {
         _extension(GL,ARB,draw_instanced,               GL210, GL310) // #44
         _extension(GL,ARB,framebuffer_object,           GL210, GL300) // #45
         _extension(GL,ARB,geometry_shader4,             GL210, GL320) // #47
+        _extension(GL,ARB,half_float_vertex,            GL210, GL300) // #48
         _extension(GL,ARB,instanced_arrays,             GL210, GL330) // #49
         _extension(GL,ARB,map_buffer_range,             GL210, GL300) // #50
         _extension(GL,ARB,texture_buffer_object,        GL210, GL310) // #51
@@ -207,7 +208,6 @@ namespace GL {
         _extension(GL,KHR,context_flush_control,        GL210, GL450) // #168
         _extension(GL,KHR,robustness,                   GL320, GL450) // #170
     } namespace NV {
-        _extension(GL,NV,half_float,                    GL210, GL300) // #283
         _extension(GL,NV,primitive_restart,             GL210, GL310) // #285
         _extension(GL,NV,depth_buffer_float,            GL210, GL300) // #334
         _extension(GL,NV,conditional_render,            GL210, GL300) // #346

src/Magnum/Test/MeshGLTest.cpp

@@ -896,8 +896,8 @@ void MeshGLTest::addVertexBufferIntWithShort() {
 
 void MeshGLTest::addVertexBufferFloatWithHalfFloat() {
     #ifndef MAGNUM_TARGET_GLES
-    if(!Context::current()->isExtensionSupported<Extensions::GL::NV::half_float>())
+    if(!Context::current()->isExtensionSupported<Extensions::GL::ARB::half_float_vertex>())
-        CORRADE_SKIP(Extensions::GL::NV::half_float::string() + std::string(" is not supported."));
+        CORRADE_SKIP(Extensions::GL::ARB::half_float_vertex::string() + std::string(" is not supported."));
     #elif defined(MAGNUM_TARGET_GLES2)
     if(!Context::current()->isExtensionSupported<Extensions::GL::OES::vertex_half_float>())
         CORRADE_SKIP(Extensions::GL::OES::vertex_half_float::string() + std::string(" is not supported."));