First stub of timer update done

After every game that's been won or lost, a count of the length
of the game (in seconds) is printed.

Started (and probably finished) highscore.[ch], to save and import
highscores. Added a few functions to the new files misc.[ch] as
utility functions related to highscore.*. Makefile updated to handle
these new files.

The interface has still to be upgraded to display high scores and
to take a name every time a score is to be saved.
Remove empty grid_solver.c and update Makefile

Minor changes to the Makefile; grid_solver.c was empty, so no need
to keep it anymore.
Finish first draft of highscore implementation

It's a really rough implementation, but should work.
Testing has *not* been done and should be considered if
nothing is changed for a while.
Remove debugging prints

Various printfs commented out and some testing done;
apparently everything works fine, though the implementation
must still be completed.

Specifically, as of now there's no way to save the score
with a name (though highscore.h supports the feature).
The feature should be supported by creating a new interface
function to get a word while showing the current scores.
create first stub of timer.*

Created basic functions of timer.*; the interface has to be
updated to handle milliseconds.
Complete timer.* complete, updated interface

Interface updated to handle scores with millisecond
precision.
translate the interface

The interface should now be completely in English
refactorize grid dim code and change exec name