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

Enhancement in comparison behavior + print function

untested

Set some function inlune and implement an utility function
for file searching functions.

Telling if the logfile array is sorted

ttail_set_flag_re_ex() and ttail_set_flag_re_ci()

For extended & case insensitive regex

Now we can specify a constant length to cut

The getline wrapper will allow to use getline without calling malloc
and free all the time