Remove I411 support, update doc and switch to side by side test

include/libyuv/convert.h

Index: include/libyuv/convert.h
diff --git a/include/libyuv/convert.h b/include/libyuv/convert.h
index d44485847be1d67672e84780fb29d34038dc6907..5a9368dd61efb3a6ed96c4e5bbcc0b49dd36900c 100644
--- a/include/libyuv/convert.h
+++ b/include/libyuv/convert.h
@@ -45,16 +45,6 @@ int I422ToI420(const uint8* src_y, int src_stride_y,
                uint8* dst_v, int dst_stride_v,
                int width, int height);
 
-// Convert I411 to I420.
-LIBYUV_API
-int I411ToI420(const uint8* src_y, int src_stride_y,
-               const uint8* src_u, int src_stride_u,
-               const uint8* src_v, int src_stride_v,
-               uint8* dst_y, int dst_stride_y,
-               uint8* dst_u, int dst_stride_u,
-               uint8* dst_v, int dst_stride_v,
-               int width, int height);
-
 // Copy I420 to I420.
 #define I420ToI420 I420Copy
 LIBYUV_API