mshow: add "-A all" to render all attachments

Closes #198.

contrib/_mblaze

@@ -346,7 +346,7 @@ _mshow() {
     - regular \
       '-n[only print message numbers]' \
       '-h[display only given headers]:header list:_mblaze_colon_separated_headers' \
-      '-A[mixed/alternative preference]:mime type: ' \
+      '-A[multipart/alternative preference]:mime type: ' \
       '-n[don'\''t update current message link]' \
       '(-r)-q[print only header]' \
       '(-q)-r[print body raw]' \

man/mshow.1

@@ -1,4 +1,4 @@
-.Dd August 24, 2018
+.Dd January 17, 2021
 .Dt MSHOW 1
 .Os
 .Sh NAME
@@ -47,17 +47,26 @@ instead of the default headers
 .Sq Li from\&:subject\&:to\&:cc\&:date\&:reply\&-to\&: .
 .It Fl A Ar mimetypes
 Define
-.Sq Li "mixed/alternative"
+.Sq Li "multipart/alternative"
 preference.
 .Ar mimetypes
 is a colon-separated list of
 MIME types which will be preferred,
 in the order given,
 when rendering
-.Sq Li "mixed/alternative"
+.Sq Li "multipart/alternative"
 parts.
 If no MIME type matches, the first MIME part will be rendered.
 .Pp
+When
+.Ar mimetypes
+is
+.Sq Li all ,
+.Nm
+will render all parts of a
+.Sq Li "multipart/alternative"
+part.
+.Pp
 Defaults to
 .Sq Li "text/plain:text/html" .
 .It Fl n

mshow.c

@@ -316,9 +316,10 @@ nofilter:
 			}
 			printf("\n");
 		} else if (strncmp(ct, "multipart/alternative", 21) == 0) {
-			choose_alternative(msg, depth);
+			if (strcmp(Aflag, "all") != 0) {
-
+				choose_alternative(msg, depth);
-			r = MIME_PRUNE;
+				r = MIME_PRUNE;
+			} // else default blaze822_mime_walk action
 		} else if (strncmp(ct, "multipart/", 10) == 0) {
 			; // default blaze822_mime_walk action
 		} else {