Merge 'Fullscreen' and 'Toggle fullscreen' shortcut.

git-svn-id: svn+ssh://svn.code.sf.net/p/mcomix/code@917 ef8490bc-f317-4725-81ed-e95a9aca1bcf
Fix variable scope.

git-svn-id: svn+ssh://svn.code.sf.net/p/mcomix/code@918 ef8490bc-f317-4725-81ed-e95a9aca1bcf