*: refactor handling of archived files. "tar f file.tar.lzma" now works too.

function                                             old     new   delta
unpack_Z_stream                                        -    1229   +1229
open_zipped                                            -     176    +176
unpack_bz2_stream_prime                                -      60     +60
tar_main                                             642     677     +35
find_main                                            406     418     +12
sv_main                                             1222    1233     +11
decode_format_string                                 829     837      +8
cmp_main                                             641     649      +8
popstring                                            134     140      +6
filter_accept_list_reassign                          120     125      +5
parse_and_put_prompt                                 800     804      +4
passwd_main                                         1053    1049      -4
make_new_name_gunzip                                 119     114      -5
rpm_main                                            1688    1670     -18
prepare                                              302     283     -19
xmalloc_open_zipped_read_close                       135      61     -74
uncompress                                          1229       -   -1229
------------------------------------------------------------------------------
(add/remove: 3/1 grow/shrink: 8/5 up/down: 1554/-1349)        Total: 205 bytes

1 files changed, 7 insertions, 7 deletions

diff --git a/include/usage.h b/include/usage.h
index ae6d2bcb6..78f40367e 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -3943,9 +3943,9 @@
        "nameserver 10.0.0.1\n"
 
 #define tar_trivial_usage \
-       "-[" USE_FEATURE_TAR_CREATE("c") USE_FEATURE_TAR_GZIP("z") \
-        USE_FEATURE_TAR_BZIP2("j") USE_FEATURE_TAR_LZMA("a") \
-        USE_FEATURE_TAR_COMPRESS("Z") "xtvO] " \
+       "-[" USE_FEATURE_TAR_CREATE("c") USE_FEATURE_SEAMLESS_GZ("z") \
+        USE_FEATURE_SEAMLESS_BZ2("j") USE_FEATURE_SEAMLESS_LZMA("a") \
+        USE_FEATURE_SEAMLESS_Z("Z") "xtvO] " \
         USE_FEATURE_TAR_FROM("[-X FILE] ") \
        "[-f TARFILE] [-C DIR] [FILE(s)]..."
 #define tar_full_usage "\n\n" \
@@ -3956,16 +3956,16 @@
      "\n        x       Extract" \
      "\n        t       List" \
      "\nArchive format selection:" \
-        USE_FEATURE_TAR_GZIP( \
+        USE_FEATURE_SEAMLESS_GZ( \
      "\n        z       Filter the archive through gzip" \
         ) \
-        USE_FEATURE_TAR_BZIP2( \
+        USE_FEATURE_SEAMLESS_BZ2( \
      "\n        j       Filter the archive through bzip2" \
         ) \
-        USE_FEATURE_TAR_LZMA( \
+        USE_FEATURE_SEAMLESS_LZMA( \
      "\n        a       Filter the archive through lzma" \
         ) \
-        USE_FEATURE_TAR_COMPRESS( \
+        USE_FEATURE_SEAMLESS_Z( \
      "\n        Z       Filter the archive through compress" \
         ) \
      "\nFile selection:" \