standardized dialog for guider 'Control Parameters' &'Other Settings'

Before the refactor of the guiding modules by Hy Murvit it was necessary to implement a special handling for parameters like Proportional Gain, Integral Gain, etc. The dialog of these parameters was in the main guidedialog and did not have an Apply- and OK-button. After the refactor they are placed in a sub-KConfigPage with Apply- and OK-button and it is very confusing to use two different schemes: 'Control Parameters' uses direct saving and 'Other Settings' uses the built-in saving of KConfigDialog via 'kcfg'-variables! This MR use 'kcfg'-variables throughout the whole dialog. In addition using these variables simplifies the code a lot because saving is handled automatically.