Summary of feature request description

* actual behaviour:

1. When changing properties in the DataManager one must click twice on a table cell.
2. When editing numeric property value with the QSpinBox(es) in the table one can only change the value in the default 
minimum() and maximum() range of Qt`s SpinBox.

* expected behaviour

1. A single click on a cell should be sufficient.
2. Numeric values should be adjustable between their lower and upper limits.

Cause of the bug

1. Feature Request
2. Forgetfulness of the programmer

Proposed solution

1. Add Qt::SelectionChanged to the QAbsractItemView-editingFlags
2. When creating spin boxes set the minimum and maximum to the numeric limits

How will the bugfix get tested?

1. -
2. Application test of setting numeric values to its limits