'loads data from files written and return a data dictionary, *not*
a prerequisite for using `plot()` or `disp()`.
Argument `filenameprefix` is the filename prefix of data to be loaded (five files),
by default ``\'outcmaes\'``.
Return data dictionary with keys `xrecent`, `xmean`, `f`, `D`, `std`'

def load(self, filenameprefix=None):

    if (not filenameprefix):
        filenameprefix = self.name_prefix
    dat = self
    dat.xmean = _fileToMatrix((filenameprefix + 'xmean.dat'))
    dat.std = _fileToMatrix(((filenameprefix + 'stddev') + '.dat'))
    for key in ['xmean', 'std']:
        dat.__dict__[key].append(dat.__dict__[key][(-1)])
        dat.__dict__[key] = array(dat.__dict__[key], copy=False)
    dat.f = array(_fileToMatrix((filenameprefix + 'fit.dat')))
    dat.D = array(_fileToMatrix(((filenameprefix + 'axlen') + '.dat')))
    return dat
