Start working on script editor help
Add get_word_under_cursor() method to TextEdit
EditorNode consume F1 key only when Shift or Command key not pressed at the same time
Update EditorHelp to response help request other than class; Make sure EditorHelpSearch dialog popup with search results
Implement Shift+F1 as contextual help hotkey for script editor; There's
one bug that when jump to help tab first time, the scroll position is
wrong.
Merge pull request #373 from marynate/PR-contextual-help

Contextual help for Script Editor