Header: added icons for new game and modify game buttons

added icon files for new game and modify game buttons

Reported-by: bnurbekov
Signed-off-by: Batyrlan Nurbekov <bnurbekov@wpi.edu>
Merge pull request #38 from bnurbekov/sbl-dev

Header: added icons for new game and modify game buttons
Merge remote-tracking branch 'upstream/sbl-dev' into sbl-dev