Sqr, Sqrt, Cube, Cbrt now have 1-char ITextOut mathRender

We now can include arbitrary unicode characters into text strings of
arbitrary fonts (as we always use composite fonts and do not depend
on the limited character range of a given font anymore), as of the
previous commits. Therefore, we chose to represent Sqr, Sqrt, Cube,
and Cbrt by the corresponding unicode characters instead of function
names (no longer "sqrt(x)") and powers ("²" instead of "x^2").

src/main/java/org/optimizationBenchmarking/utils/math/functions/power/Cbrt.java

@@ -62,9 +62,8 @@ public final Cube invertFor(final int index) {
   @Override
   public final void mathRender(final ITextOutput out,
       final IParameterRenderer renderer) {
-    out.append("cbrt("); //$NON-NLS-1$
+    out.append((char) 0x221b);
     renderer.renderParameter(0, out);
-    out.append(')');
   }
 
   /** {@inheritDoc} */

src/main/java/org/optimizationBenchmarking/utils/math/functions/power/Cube.java

@@ -157,8 +157,7 @@ public final Cbrt invertFor(final int index) {
   public final void mathRender(final ITextOutput out,
       final IParameterRenderer renderer) {
     renderer.renderParameter(0, out);
-    out.append('^');
-    out.append('3');
+    out.append((char) 0xb3);
   }
 
   /** {@inheritDoc} */

src/main/java/org/optimizationBenchmarking/utils/math/functions/power/Sqr.java

@@ -133,8 +133,7 @@ public final Sqrt invertFor(final int index) {
   public final void mathRender(final ITextOutput out,
       final IParameterRenderer renderer) {
     renderer.renderParameter(0, out);
-    out.append('^');
-    out.append('2');
+    out.append((char) 0xb2);
   }
 
   /** {@inheritDoc} */

src/main/java/org/optimizationBenchmarking/utils/math/functions/power/Sqrt.java

@@ -126,7 +126,7 @@ public final Sqr invertFor(final int index) {
   @Override
   public final void mathRender(final ITextOutput out,
       final IParameterRenderer renderer) {
-    out.append("sqrt("); //$NON-NLS-1$
+    out.append((char) 0x221a);
     renderer.renderParameter(0, out);
     out.append(')');
   }