Making display of x axis cofigurable

Summary:
Some optimizations for the display of sensor data:

• The range displayed on the y axis is either limited by the value range or - configurable - including the x axis.
• Bugfix - action timer starts only when at least one action is selected.
• Layout optimizations

Reviewers: mutlaqja

Reviewed By: mutlaqja

Subscribers: kde-edu

Tags: KDE Edu

Differential Revision: https://phabricator.kde.org/D25007