Added documentation files.

Signed-off-by: Kristian Duske <kristian.duske@gmail.com>
Allow map properties dialog to be closed with Cmd+W on Mac.

Signed-off-by: Kristian Duske <kristian.duske@gmail.com>
More documentation.

Signed-off-by: Kristian Duske <kristian.duske@gmail.com>
Don't allow undefined hidden entities to be selected.

Signed-off-by: Kristian Duske <kristian.duske@gmail.com>