Do not enable texture_clean_transparent by default

This feature is still experimental and has some issues. Also,
increase texture_min_size to 64 px. The setting was initially
a conservative 16 so that the effect would not be noticable
for players who aren't using aniso/bi/trilinear filtering. This
isn't necessary now that texture_clean_transparent is disabled
by default.

minetest.conf.example

@@ -197,7 +197,7 @@
 #    which PNG optimizers usually discard, sometimes resulting in a dark or
 #    light edge to transparent textures.  Apply this filter to clean that up
 #    at texture load time.
-#texture_clean_transparent = true
+#texture_clean_transparent = false
 #    When using bilinear/trilinear/anisotropic filters, low-resolution textures
 #    can be blurred, so automatically upscale them with nearest-neighbor
 #    interpolation to preserve crisp pixels.  This sets the minimum texture size
@@ -205,7 +205,7 @@
 #    memory.  Powers of 2 are recommended.  Setting this higher than 1 may not
 #    have a visible effect unless bilinear/trilinear/anisotropic filtering is
 #    enabled.
-#texture_min_size = 16
+#texture_min_size = 64
 #    Set to true to pre-generate all item visuals
 #preload_item_visuals = false
 #    Set to true to enable shaders. Disable them if video_driver = direct3d9/8.

src/defaultsettings.cpp

@@ -149,8 +149,8 @@ void set_default_settings(Settings *settings)
 	settings->setDefault("anisotropic_filter", "false");
 	settings->setDefault("bilinear_filter", "false");
 	settings->setDefault("trilinear_filter", "false");
-	settings->setDefault("texture_clean_transparent", "true");
-	settings->setDefault("texture_min_size", "16");
+	settings->setDefault("texture_clean_transparent", "false");
+	settings->setDefault("texture_min_size", "64");
 	settings->setDefault("preload_item_visuals", "false");
 	settings->setDefault("enable_bumpmapping", "false");
 	settings->setDefault("enable_parallax_occlusion", "false");