a) add a new function
hra_core.misc.is_positive(value)
to check if a value is positive number (>=0);
use this function  for signal_index, annotation_index and time_index
members  of poincare plot

b) package hra_math.time_domain.poincare_plot.poincare_plot:
change input data separator of poincare plot, named  as (-p) to longer
version named as (-separator);
manage this parameter - pass it into DataVectorFileDataSource objects

c) moved property separator from class
hra_math.model.parameters.file_data_parameters.FileDataParameters
into 
hra_math.model.parameters.data_vector_parameters.DataVectorParameters