opensim-core: DataTable::getRow() should not perform equality comparison on double

DataTable::getRow() uses std::find() to search for a specified entry in the independent column. When the independent variable is of type double (e.g., time, as will often be the case), std::find() must include a tolerance (e.g., using std::find_if()). Currently, filling a TimeSeriesTable with time points spaced 0.01 seconds apart and doing

for (unsigned i=0u; i<table.getNumRows(); ++i)
    table.getRow(0.01*i);

throws KeyNotFound when i=6u due to roundoff error.