Remove default edge to getCharacterPosition()

To prevent confusion, remove default edge=true which forces callers
to specify all parameter.

src/TerminalDisplay.cpp

@@ -2469,7 +2469,7 @@ void TerminalDisplay::extendSelection(const QPoint& position)
 
     int charColumn = 0;
     int charLine = 0;
-    getCharacterPosition(pos, charLine, charColumn);
+    getCharacterPosition(pos, charLine, charColumn, true);
 
     QPoint here = QPoint(charColumn, charLine);
     QPoint ohere;
@@ -3090,7 +3090,7 @@ void TerminalDisplay::mouseTripleClickEvent(QMouseEvent* ev)
 
     int charLine;
     int charColumn;
-    getCharacterPosition(ev->pos(), charLine, charColumn);
+    getCharacterPosition(ev->pos(), charLine, charColumn, true);
     selectLine(QPoint(charColumn, charLine),
                _tripleClickMode == Enum::SelectWholeLine);
 }

src/TerminalDisplay.h

@@ -862,7 +862,7 @@ private:
     // maps a point on the widget to the position ( ie. line and column )
     // of the character at that point. When the edge is true, it maps to
     // a character which left edge is closest to the point.
-    void getCharacterPosition(const QPoint &widgetPoint, int &line, int &column, bool edge = true) const;
+    void getCharacterPosition(const QPoint &widgetPoint, int &line, int &column, bool edge) const;
 
     // the area where the preedit string for input methods will be draw
     QRect preeditRect() const;