Original commit message from CVS:
* ext/libpng/gstpngdec.c: (gst_pngdec_src_getcaps):
* ext/libpng/gstpngenc.c: (gst_pngenc_class_init),
(gst_pngenc_init), (gst_pngenc_chain), (gst_pngenc_get_property),
(gst_pngenc_set_property):
* ext/libpng/gstpngenc.h:
Added snapshot property to pngenc.
removed g_print from pngdec