Decrease calculation interval for ascend speed: In the previous version the ascend speed was calculated every 2 seconds. To improve the visualization the interval has been reduced to 400ms. The average function of the depth calculation ensures a smooth dynamic transition of the values. For testing a simulation profile, which changes between several speeds, may be acivated using the compile switch.

Imported from Ac6/SystemWorkbench/plugins/fr.ac6.mcu.firmware_1.14.7.201711101414/resources/builtin/:
* File syscalls.c