tmac: rename IM (italic manual) to MR (manual reference)

Suggested by G. Brandon Robinson.

man/man3/dsa.3

@@ -84,7 +84,7 @@ and
 generated by
 .IR DSAprimes
 (see
-.IM prime (3) ).
+.MR prime (3) ).
 Otherwise,
 .B p
 and
@@ -128,17 +128,17 @@ are provided to manage signature storage.
 converts an ASN1 formatted DSA private key into the corresponding
 .B DSApriv
 structure; see 
-.IM rsa (3)
+.MR rsa (3)
 for other ASN1 routines.
 .SH SOURCE
 .B \*9/src/libsec
 .SH SEE ALSO
-.IM mp (3) ,
-.IM aes (3) ,
-.IM blowfish (3) ,
-.IM des (3) ,
-.IM rc4 (3) ,
-.IM rsa (3) ,
-.IM sechash (3) ,
-.IM prime (3) ,
-.IM rand (3)
+.MR mp (3) ,
+.MR aes (3) ,
+.MR blowfish (3) ,
+.MR des (3) ,
+.MR rc4 (3) ,
+.MR rsa (3) ,
+.MR sechash (3) ,
+.MR prime (3) ,
+.MR rand (3)