Changes:
- Allow panoramic scrolling by left drag in fullscreen mode.
- Restore cell pixel size when switching to/from fullscreen mode if the size has been changed.
- Changing the cell size in normal mode resets the fullscreen cell size.
- Fix default GUI-window position and size (don't rely on parent console window).
<config> <gui> <!-- GUI related settings. (win32 platform only for now) --> <gridsize=""/> <!-- Window initial grid size "width,height" in text cells. If gridsize="" or gridsize=0,0, then the size of the GUI window is left to the OS window manager. --> <wincoor=""/> <!-- Window initial coordinates "x,y" (top-left corner on the desktop in physical pixels). If wincoor="", then the position of the GUI window is left to the OS window manager. --> </gui> <config>