Fixed some problems with generation of C++ code.

Representations such as ode now appear to have multiple outputs (mttdx,mtty) listed in mtt_header, so the write_cc_header parses the string and only returns the first one.

Vector sizes mttnu, mttnx, etc. now appear in the code of sys_ode.m etc., so they are declared as static int in sys_def.h.

The following now works properly on Ubuntu 12: mtt -cc -i euler -o rc gnuplot view