restore all panel properties
Summary:
restore the missing panel properties:
alignment
minimum length
maximum length
offset
also, allow non integer values for the measures (height, min/max, offset)
BUG:368074
BUG:367918
Test Plan:
dumped a config with a custom panel, different height/alignment/offset etc
started a new plasma session with that l&f package, restored panel correctly
Reviewers: Plasma, davidedmundson
Reviewed By: Plasma, davidedmundson
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D3021