Add Slider Component

Additions

• New slider component (#284): see documentation

• New power_source_change event that is fired on changes in the power source and makes less aggressive power state polling possible, as can be seen in the default config battery item.
• Add more checks to verify validity of item name, position and type
• Add a topmost setting for popups (#309)
• Add padding_left and padding_right property to first level item properties (synchronized with the items background.padding_*)
• Search functionality in documentation curtesy of @tsironis (#310)

Fixes

• Fixes an unexpected behavior with spaces and the drawing property (#307)

Changes

• Decouple the update frequency of alias and script by introducing alias.update_freq

Full Changelog: v2.12.3...v2.13.2