Task is done
Merge remote-tracking branch 'remotes/origin/Sitrus2' into DUI-OperatorsLinearList
IsPlaceHolder renamed to IsPlaceholder
Merge remote-tracking branch 'remotes/origin/Sitrus2' into DUI-OperatorsLinearList
ProcessRootCategories function removed
Added comments to LibraryView.xaml
Reverted peace of code from another PR
ClassDetailsVisibility made read-only
Merge pull request #37 from vmoyseenko/DUI-OperatorsLinearList

Built-in functions/Operators should be a linear list