Added general utilities to estimate the change in memory for executing a command by wrapping the command and getCurrentRSS() in a loop and computing the median change.
Added general utilities to estimate the change in memory for executing a command by wrapping the command and getCurrentRSS() in a loop and computing the median change.

Also added a method to test that getRSS is valid by testing against a known block size that is malloced.

opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core,opensim-org/opensim-core