Timing command to measure simulation time

[Per Östlund]

There currently exists a timing API call that measures the time it takes for a command to run, but running timing(simulate(...)) will measure not only the simulation time but also flattening, code generation and compilation. It would be helpful to have some way of measuring only the simulation time, i.e. the time it takes to run the simulation executable, since it's common to want to compare OMC simulation times with other tools. At the moment this must be done with external tools such as Linux's time command. This could be either a separate API call or an added option to simulate.

[Martin Sjölund]

Fixed in r6075 (SimulationResult contains more information than before)