Preserve current line when resetting

Reset was always called with clearScreen = true, so no point in having
that variable. We can probably also remove Screen::clear() and
Screen::home(), they're not used anymore, and weren't really useful
before this either.

We still preserve the scrollback history when resetting, which is not
what other terminal emulators do (http://stackoverflow.com/a/5367075),
but we do have a separate action for it, so I think it is a nice extra
feature to preserve it.

REVIEW: 128389

src/Screen.cpp

@@ -513,14 +513,18 @@ QVector<LineProperty> Screen::getLineProperties(int startLine , int endLine) con
     return result;
 }
 
-void Screen::reset(bool clearScreen)
+void Screen::reset()
 {
+    // Clear screen, but preserve the current line
+    scrollUp(0, _cuY);
+    _cuY = 0;
+
+    _currentModes[MODE_Origin] = false;
+    _savedModes[MODE_Origin] = false;
+
     setMode(MODE_Wrap);
     saveMode(MODE_Wrap);      // wrap at end of margin
 
-    resetMode(MODE_Origin);
-    saveMode(MODE_Origin);  // position refer to [1,1]
-
     resetMode(MODE_Insert);
     saveMode(MODE_Insert);  // overstroke
 
@@ -531,11 +535,11 @@ void Screen::reset(bool clearScreen)
     _topMargin = 0;
     _bottomMargin = _lines - 1;
 
+    // Other terminal emulators reset the entire scroll history during a reset
+//    setScroll(getScroll(), false);
+
     setDefaultRendition();
     saveCursor();
-
-    if (clearScreen)
-        clear();
 }
 
 void Screen::clear()

src/Screen.h

@@ -334,7 +334,7 @@ public:
      * If @p clearScreen is true then the screen contents are erased entirely,
      * otherwise they are unaltered.
      */
-    void reset(bool clearScreen = true);
+    void reset();
 
     /**
      * Displays a new character at the current cursor position.