adding touch hander class as new DRV_TOUCH to enable user specific touch

[espHorst]

As discussed here a PR adding a new touch handler class.
The touch handler class is included as an own driver into GUIslice which can be selected as the other drivers via defines.
The user can now add a own touch driver just by performing the steps below.
Thus no modification / adoption of the GUIslice library itself is required to test / add a new touch driver.

To create a new user specific touch handler

• copy the full functional example GUIslice_th_XPT2046.h to the user application directory
• rename it
• adopt it to the specific touch display

In the user program (I have added an example arduino gslc_ex11_ard_touch_handler) just

• include your adopted touch handler
• instantiate your touch handler
• call gslc_InitTouchHandler(&touchHandler);

I have successfully tested the touch handler with a STM32F1 and a 2.4" TFT SPI 240x320.
Please have I look at the text headers of the files, I did not know what has to be added.

[ImpulseAdventure]

Looks good.

I tested this in the regression and it appears OK with Arduino_STM32, Adafruit-GFX-AS and the Generic STM32F103C8 target.

Note that I may rename gslc_ex11_ard_touch_handler later to gslc_ex11_ard for consistency.

Thanks!

[ImpulseAdventure]

(Duplicate comment due to GutHub issue)