Created SingleParameterSignal template.
Minimalistic documentation improvment.
Fixed missing function parameters in SingleParameterSignal.
Added documentation to SingleParameterSignal::connect().
Added Widget::signalkeypressed signal.
Moved key board handling for Cursor movement from GuiHandler to BoardWidget.
Moved placing/moving entities when return is hit from DeployWindow to BoardWidget.
Added Window::handleEvent().
Improved code readability in Window::draw().
Removed now deprecated and unused code from DeployWindow.