Added the opportunity to plot some graphs quantity in the same window ('plotGraphsSameWin' variable).

Main features:
- the plot graphics code moved from the src/define_oil_characteristics.sce
  source file to the src/special_functions.sci source file in the function
  'plotResults';
- now user can plot some graphs quantity in the same (one) window.
  This quantity value setted in the code of 'plotResults' function
  ('graphsOnWin' variable). This functionality allows to take away the
  scilab hang-up when every graphs ploting in the individual window;
- fixed - in the src/define_oil_characteristics.sce source file the control
  of a state the 'importSteady' variable moved from the 'Save results in a
  text file' section to the section 'Export steady mode points in a text file';
- in the src/define_oil_characteristics.sce source file the parameters
  values, that can have only values 'yes/no', replaced from '1/0' to
  'true/false' (%T/%F).

Signed-off-by: Oleg <olgerd27@gmail.com>
Corrected the plotted windows size and position.

Signed-off-by: Oleg <olgerd27@gmail.com>