Move lower case functions into wrapper.c

The lowercase() function from config.c and the xstrdup_tolower()
function from daemon.c can benefit from being moved to the same
place because this way the latter can use the former.

Also let's make them available globally so we can use them from
other places like trailer.c.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
trailer: read and process config information

Read the configuration to get trailer information, and then process
it and storing it in a doubly linked list.

The config information is stored in the list whose first item is
pointed to by:

static struct trailer_item *first_conf_item;

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
trailer: process command line trailer arguments

Parse the trailer command line arguments and put
the result into an arg_tok doubly linked list.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
trailer: parse trailers from stdin

Read trailers from stdin, parse them and put the result into a doubly linked
list.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
trailer: put all the processing together and print

This patch adds the process_trailers() function that
calls all the previously added processing functions
and then prints the results on the standard output.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
trailer: add interpret-trailers command

This patch adds the "git interpret-trailers" command.
This command uses the previously added process_trailers()
function in trailer.c.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
trailer: add tests for "git interpret-trailers"

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
trailer: execute command from 'trailer.<name>.command'

Let the user specify a command that will give on its standard output
the value to use for the specified trailer.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
trailer: add tests for commands in config file

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
trailers: add documentation for 'git interpret-trailers'

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>