Added two new scroll bar types. Fixed for ListView
with equal height elements and PreRendered which
require whole list render - not recommended for big
lists but works with not equal heights elements.
Applied new types to all lists in Pure. Various
cleanups and refactors inside models and listView.
* Timers now are Application thread safe
* Timers now have consistent API independend of Application (no more c style timers)
* Timers can have either: callback or override onTimer() method - this
way we can create more complicated timers or just use existing ones
* gui::Timer added via adapter class GuiTimer to decouple sys::Timer
with gui::Timer
* Fixed race in wrapper
* Updated docs
* fixed using std and cpp_freertos and DataReceivedHandler hidden in Application.hpp
