This mode is purely for animated map movies -- the user can set
the total number of frames, and the animation will progress
frame by frame for that number of frames, advancing the current
map settings frame at each step (also the @frame_number expression
variable).
No time based filtering of data is performed when in this mode.
Move vector, project and network related core .cpp/.h files into
dedicated subdirectories.
An attempt to organise src/core better to make things easier to find.
