Shaders: update DistanceFieldVector test files with fixed SDFs.

The output is now *much* closer to the Vector shader output (mean
difference went from ~6 to 1.79), and in the multi-draw case it's
clearly visible that it's no longer slightly weirdly uneven.

The test files are now also much smaller as the originals were created
before RLE was implemented in TgaImageConverter.

src/Magnum/Shaders/Test/DistanceFieldVectorGLTest.cpp

@@ -869,14 +869,13 @@ template<DistanceFieldVectorGL2D::Flag flag> void DistanceFieldVectorGLTest::ren
 
     MAGNUM_VERIFY_NO_GL_ERROR();
 
-    /* Should be almost the same as Shaders::Vector output, but due to various
-       differences in the SDF output and too sharp default shininess it can't
-       be exact */
+    /* Should be almost the same as Shaders::Vector output, but due to too
+       sharp default shininess it can't be exact */
     CORRADE_COMPARE_WITH(
         /* Dropping the alpha channel, as it's always 1.0 */
         Containers::arrayCast<Color3ub>(_framebuffer.read(_framebuffer.viewport(), {PixelFormat::RGBA8Unorm}).pixels<Color4ub>()),
         Utility::Path::join(_testDir, "VectorTestFiles/defaults.tga"),
-        (DebugTools::CompareImageToFile{_manager, 201.0f, 6.1f}));
+        (DebugTools::CompareImageToFile{_manager, 131.0f, 1.83f}));
 
     #if !(defined(MAGNUM_TARGET_GLES2) && defined(MAGNUM_TARGET_WEBGL))
     /* SwiftShader has off-by-one differences on edges, ARM Mali off-by-one in
@@ -980,14 +979,13 @@ template<DistanceFieldVectorGL3D::Flag flag> void DistanceFieldVectorGLTest::ren
 
     MAGNUM_VERIFY_NO_GL_ERROR();
 
-    /* Should be almost the same as Shaders::Vector output, but due to various
-       differences in the SDF output and too sharp default shininess it can't
-       be exact */
+    /* Should be almost the same as Shaders::Vector output, but due to too
+       sharp default shininess it can't be exact */
     CORRADE_COMPARE_WITH(
         /* Dropping the alpha channel, as it's always 1.0 */
         Containers::arrayCast<Color3ub>(_framebuffer.read(_framebuffer.viewport(), {PixelFormat::RGBA8Unorm}).pixels<Color4ub>()),
         Utility::Path::join(_testDir, "VectorTestFiles/defaults.tga"),
-        (DebugTools::CompareImageToFile{_manager, 201.0f, 6.1f}));
+        (DebugTools::CompareImageToFile{_manager, 131.0f, 1.83f}));
 
     #if !(defined(MAGNUM_TARGET_GLES2) && defined(MAGNUM_TARGET_WEBGL))
     /* SwiftShader has off-by-one differences on edges, ARM Mali off-by-one in