Enhance visibility of P and Q values

Prior to this ticket, the power of BaseLoad was written as P + j Q in one row.
Unfortunately, the available space is limited, and therefore these values were hardly seen in thiagrams. The situation was worsened by the fact that the width of the text rectangle containing the label did not span the entire icon width.
This commit introduces three changes:
1. puts the values of P and Q in two lines to gain them more space
2. enlarges the text rectangle to contribute to give more space for display as well
2. converts the text colour into black, since the de-facto standard used in the Modelica Standard Library is to use black for parameter values.

Author: ceraolo

OpenIPSL/Electrical/Loads/PSAT/BaseClasses/baseLoad.mo

@@ -26,10 +26,13 @@ equation
   annotation (Icon(coordinateSystem(preserveAspectRatio=false, extent={{-100,-100},
             {100,100}}), graphics={Line(points={{-100,100},{100,100},{0,-100},{
           -100,100}}, color={28,108,200}),Text(
-          extent={{-60,80},{60,40}},
-          lineColor={28,108,200},
-          textString="%P_0+j%Q_0"),Text(
+          extent={{-100,80},{100,56}},
+          lineColor={0,0,0},
+          textString="%P_0"),      Text(
           extent={{-150,-110},{150,-150}},
           lineColor={0,0,255},
-          textString="%name")}));
+          textString="%name"),            Text(
+          extent={{-100,32},{100,6}},
+          lineColor={0,0,0},
+          textString="%Q_0")}));
 end baseLoad;