set_relative_date was failing if the resulting date was in the previous
day.

Following PR #19

Add some usefull functions & macro in ttail_check.h for std tests.

And updated doxygen todo list

And bugfixes in _ttail_set_date_relative() bad format detection

In order to not install them.

Now ttail is able to sort logfiles given as arguement.
The sort function _ttail_file_sort place files with no valid date to the
end of the file list and is able to detect if some files overlaps.

No tests written...

But not by alphabetical order :P

Not 100% sur of implementation. And the feature seems a bit useless..

Adds the option -P --permissive.

Starts implementation for logfiles.

Now -P flag make ttail handle invalid files. When invalid file given the
minmax function set the file pointer and the minmax array to NULL.

May introduce bugs if the binary search function does not handles "holes"
in fp array or in minmax array...

Telling getopt to produce an error message by setting opterr to 1

The manpage update was broken. Now make docs updates the manpage.

Date detection on stdin enabled

Not done for stdin

Making this function usable by logfiles and stdin format autodetection

Seems to work with stdin

Date formats

        Two date formats are allowed for dates arguments (-d , -m) :
        - the same than in the logfile
        - relative from now prefixing the argument with '#-' and given a unit
                - y : year
                - M : Month
                - d : day
                - h : hour
                - m : min
                - s : sec

Segfault was thrown when no files were found with matching date

Now ttail return an error if the whole date given in argument is not
matched by the format

Now an error is triggered if date-min > date-max
Bugfix on date-max searching (on multiple loglines with a date == date-max)

Add some perror calls

Deleted old argument struct tm* from search function (now using infos
stored in ttail_t.session )

add a -h --help option, deleted -l --logfile options
+ spliting the ttail_search_closest() & ttail_search_print_res() functions

To handle case where none of the file given as argument is readable

Now we have a running minimal ttail :
src/ttail -d "Mar 6 00:29" -f '%B%n%d %H:%M' -l tests/samples/1.log -l tests/samples/1.1.log

Testing ttail_search_closest_files() on multiple files