PlotEquiMap, PlotStereoMap: Bug in automatic computation of bar limits.

As reported by @rcruzgar , some times the extreme values are painted with NA colour. For example, if the minimum value in the input data is -0.0046, the bar limit is set to -0.004 (by rounding) and then all values below this extreme are painted with the NA colour.

@rcruzgar , can you please add any example code or plot file if you have it?