2 commands for speed manager
3 create data files containing some train data
4 write trivial initial settlement to get data array right
5 write out layout data on crash
6 check that everything in Train and Segment is init'd
8 dunno but maybe before can test
9 train speed curve measurements
12 things not yet considered at all in safety code
13 coming up against points the wrong way
14 min. curve specifications
16 initialise safety_state with appropriate stuff