[BUGFIX] Root page is always active with useShortcutData

When the root page is a regular page and has a shortcut pointing at it to make it visible in the menu it would always be active.
Merge pull request #174 from bjo3rnf/ischildpage

[FEATURE] Add IsChildPage condition ViewHelper
[TASK] Guard against empty/zero page UID passed to pageSelect
Merge pull request #176 from NamelessCoder/pageuid

[TASK] Guard against empty/zero page UID passed to pageSelect
Merge pull request #175 from bjo3rnf/rootlinefix

[BUGFIX] Root page is always active with useShortcutData