Fixed compile against Qt 4

filesystemwatcher.cpp:78:26: error: invalid use of incomplete type ‘struct QStringList’
Watch maps for changes and support reloading

The reload happens automatically when there are no currently unsaved
changes. It can also be triggered manually from the File menu. When
there are unsaved changes, the user is notified about changes to the map
file by a non-modal popup.

Sponsored-by: FlatRedBall.com