(should consider this for binary_c!)

remove debugging statements

fixed contact_system to avoid double event call which led to failure. Given that contact_system is expected to be called *only* by an event, the comenv part inside it can be called directly.

mv valgrind test script to "test_random" and added lots of options for monitoring runtimes

timestep, unset variables are not read (the RK4 was failing)

also now correctly

some things, like nucsyn and discs, only work with forward Euler,
these are now wrapped in the Forward_Euler_shot(...) macro so that
when RK2/RK4 etc. are used, these functions are only called on the
final step and then only after the final derviatives have been
calculated (and they are called for the correct timestep, not a substep)

double2bin : test return value of writes in case of failure

clean up preroche slowdown (some macros were wrong)

update and debug unit tests

fixed bug where the remnant radius because negative on weird occasions

increasd accuracy of args in log file

add support for libbacktrace
fixed SN handling (once and for all?) in mix_stars