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