GUI MaterialEditorDialog: use DoubleSpinBox

• use DoubleSpinBox instead of line edit for delta/beta or SLD
• then rm GUI::View::NumberUtil::configScientificDoubleEdit

added GUI cleanup labels

marked this issue as related to #869 (closed)

assigned to @j.wuttke

mentioned in merge request !2209 (merged)

mentioned in commit 4ddd58c5

closed with merge request !2209 (merged)