Fix faulty default theme generating oneliner.

grep | cut | perl was rather insane way of doing simple task and RE used
in perl was faulty (greedy any char separator between quotation marks).
Replace it with sed fed up via find+xargs (no -print0 for better
portability).

    find . -name '*.c' -type f | xargs sed \
        '/^[ \t]*format_add("/!d;s///;s/"[^"]*"\(.*\)".*/ \1/'

Comparison of sorted results (diff -u old new | diffstat)
- master: 6 insertions(+), 1132 deletions(-)
- 0.3.1:  6 insertions(+), 20 deletions(-)

Notable changes:

-icq_auth_subscribe  to refuse. Reason: %T%3%n
+icq_auth_subscribe %> (%1) %T%2%n asks for authorisation. Use \"/auth -a %2\" to accept, \"/auth -d %2 [reason]\" to refuse. Reason: %T%3%n

-inet_addr_failed .%n\n
+inet_addr_failed %! (%1) Invalid \"server\".%n\n

-jabber_auth_rejectnoreq  to force unauth.\n
+jabber_auth_rejectnoreq %! (%2) No pending authorization request from %T%1%n. Use \"/auth -d %1\" to force unauth.\n

-jabber_auth_subscribe  to refuse.%n\n
+jabber_auth_subscribe %> (%2) %T%1%n asks for authorisation. Use \"/auth -a %1\" to accept, \"/auth -d %1\" to refuse.%n\n

+jabber_auth_unsubscribe %> (%2) %T%1%n asks for removal. Use \"/auth -d %1\" to delete.%n\n

But there is also screwed: jabber_muc_room_created.

* docs/ekg2book-en/develbook.xml: Improve theme oneliner.
* docs/ekg2book/develbook.xml: Ditto.

docs/ekg2book-en/develbook.xml

@@ -365,9 +365,9 @@ Copyright 2000 Free Software Foundation, Inc.
          </para>
          <programlisting role="shell">
 <![CDATA[
-grep -R -I 'format_add("' * | cut -d: -f2- | \
-   perl -ne '/format_add\("(.*?)".+"(.*)".*/; print $1." ".$2."\n"' \
-   > my.theme
+find . -name '*.c' -type f | xargs sed \
+    '/^[ \t]*format_add("/!d;s///;s/"[^"]*"\(.*\)".*/ \1/' \
+    > my.theme
    ]]>
          </programlisting>
          <para>

docs/ekg2book/develbook.xml

@@ -363,9 +363,9 @@ Copyright 2000 Free Software Foundation, Inc.
          </para>
          <programlisting role="shell">
 <![CDATA[
-grep -R -I 'format_add("' * | cut -d: -f2- | \
-   perl -ne '/format_add\("(.*?)".+"(.*)".*/; print $1." ".$2."\n"' \
-   > my.theme
+find . -name '*.c' -type f | xargs sed \
+    '/^[ \t]*format_add("/!d;s///;s/"[^"]*"\(.*\)".*/ \1/' \
+    > my.theme
    ]]>
          </programlisting>
          <para>