Port chain filter to new API. Now supports chaining of chroma conversion and...

Port chain filter to new API. Now supports chaining of chroma conversion and scaling operations. Integration of crop/padding still needs to be done. This might need to be moved in the core.

modules/video_chroma/Modules.am

@@ -78,7 +78,3 @@ SOURCES_yuy2_i422 = \
 SOURCES_yuy2_i420 = \
 	yuy2_i420.c \
 	$(NULL)
-
-SOURCES_chroma_chain = \
-	chain.c \
-	$(NULL)

modules/video_filter/Modules.am

@@ -38,4 +38,5 @@ SOURCES_grain = grain.c
 SOURCES_seamcarving = seamcarving.c
 SOURCES_croppadd = croppadd.c
 SOURCES_blendbench = blendbench.c
+SOURCES_chain = chain.c
 noinst_HEADERS = filter_common.h filter_picture.h