Fix FileList navigation with keyboard (enter key focus the FileList again)
Change infinite scroll implementation

Remove necessity of jmouse_x(1) and jmouse_y(1) calls.

- Renamed jmouse_control_infinite_scroll() -> ui::control_infinite_scroll()
- Renamed jmouse_set_position() -> ui::set_mouse_position()
- Added ui::get_delta_outside_box()
Fix const-correctness for ColorPicker::pickColor() member function
Don't show grid and mask in mini editor
Don't eat all keystrokes on ui::TextBox::onProcessMessage()
Add app::StartView (work-in-progress)
Fix bug where ContextBar was completely hidden
Don't show ContextBar when the program starts
Fix bug with empty ContextBar when Ctrl+W is used to close a sprite and then a new sprite is created

This happens because Ctrl key activates the Hand/Move quick-tool, so the
ContextBar is updated to shows controls for this tool (an empty context
bar at the moment). Then, as Ctrl+W is pressed, the document is closed,
(we lost the Editor), and we willn't receive a
ContextBar::onCurrentToolChange() event (which should be generated by
releasing Ctrl key).