Replace obsolete macros with newer ones (using autoupdate)
Use a more recent version of gettext
Update some m4 macros with the latest available version
Activate some autoconf warnings
Ignore new files generated by autopoint
Game: make the constructor protected, to make the design clearer
Stats: fix a bug when the table is flipped.

The hidden rows/columns where not correctly updated.
Stats: do not display the played move in the header when the table is flipped
Stats: sort by ranking when the table is flipped
PlayWordMediator: fix header inclusion guards
PlayWordMediator: set correctly the initial state
Favorite players: add buttons to move players up and down
Hints system, to retrieve partial information about a Move.

This is only the core part, no interface integration is done yet.
New dialog to display hints to the user. Not yet used.
PlayModel: remove a TODO
PlayModel: new signal to indicate that a move is played.

This allows moving the logic out of PlayWordMediator (it will make it
easier to have a different behaviour for different mode types).
Topping: use a different method to play the move.

This allows providing additional time information
Topping: implement sorting properly
Topping: integrate hints