FAX T.6 decompression fixed for images with black in the last pixel of lines.

Colour and grey images can down be dithered down to bi-level images for transmission as faxes.
More movement towards T.42 support

libs/spandsp/src/t30_api.c

@@ -61,6 +61,7 @@
 #include "spandsp/timezone.h"
 #include "spandsp/t4_rx.h"
 #include "spandsp/t4_tx.h"
+#include "spandsp/image_translate.h"
 #include "spandsp/t81_t82_arith_coding.h"
 #include "spandsp/t85.h"
 #if defined(SPANDSP_SUPPORT_T42)
@@ -89,6 +90,7 @@
 #endif
 #include "spandsp/private/t4_t6_decode.h"
 #include "spandsp/private/t4_t6_encode.h"
+#include "spandsp/private/image_translate.h"
 #include "spandsp/private/t4_rx.h"
 #include "spandsp/private/t4_tx.h"
 #include "spandsp/private/t30.h"
@@ -700,7 +702,7 @@ SPAN_DECLARE(int) t30_set_supported_compressions(t30_state_t *s, int supported_c
          | T30_SUPPORT_T4_2D_COMPRESSION
          | T30_SUPPORT_T6_COMPRESSION
 #if defined(SPANDSP_SUPPORT_T42)
-         | T30_SUPPORT_T42_COMPRESSION
+         //| T30_SUPPORT_T42_COMPRESSION
 #endif
 #if defined(SPANDSP_SUPPORT_T43)
          | T30_SUPPORT_T43_COMPRESSION