Sudoku: use Vala's built-in support for GVariants
build: silence C compiler warnings

We have no control over these, and they only distract from the Vala
warnings.
Add ROADMAP file: design notes from IRC meeting
Implemented save game feature

Created SudokuSaver class in sudoku-saver.vala

https://bugzilla.gnome.org/show_bug.cgi?id=633464
Patch which enables 'markasPlayedToggle' and 'includeOldGamesToggle' options in multiple print dialog

https://bugzilla.gnome.org/show_bug.cgi?id=633464