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...

Not done for stdin

Seems to work with stdin

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

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

untested

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

Telling if the logfile array is sorted

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