1) changes in class hra_core.io_utils.FileSource
change property name headers_rows_count into headers_count
add w new property named headers_first_line

change in client code:
hra_math.model.numerical_file_data_source.NumericalFileDataSource
hra_math.model.text_file_data_source.TextFileDataSource

2)  changes in module:
hra_math.time_domain.poincare_plot.poincare_plot

add new parameter for poincare_plot named 
-headers_count (--headers_count)
number of headers lines in data source [default 0]
 program tries to determine this values on it's own

add management of this parameter in class
hra_math.model.parameters.data_vector_parameters.DataVectorParameters

3) changes in a class
hra_math.model.data_vector_file_data_source.DataVectorFileDataSource:
- remove superclass NumericalFileDataSource
- add new member self.__data_source__ which is set up to
TextFileDataSource 
  if time_index is present  otherwise to TextFileDataSource
- add a new method
   def __convertToFloats__(self, signal, annotation, time)
       which converts all string values in signal, annotation arrays
        into float values;  here is one assumption: time array is in
float format already