expand source files changed to add -u option so velocity variation with
area can be turned off. Also checks to stop output if CONC_A not
active.
melt - added in comments about truetimestep which came from jkb version
mike - fixed error in array declaration in oparticle.h
nucleation - edit header include statements and namespace for io
tbh, recovery - added code for updating unode attributes if present.
Previously only flynns.
statistics - tried to generalise so no crash or garbage output if
particular attributes (eg AGE) were not present
