Ros Gui stuff from Flavio
Added missing file.
Added the ability to press enter when entering the topic name and it will automatically add it to the graph
Added own QLineEdit which catches the event when the tab key is pressed.
Added tab autocompletion to the topic_edit text entry field
Extention of the QLineEdit class that catches the tab event.
Added now autocompletes and adds the / if it has only one autocompletion
Sets focus to the topic_edit textbox when the widget is created. It is a bit of a hack, but I can't set the focus until the widget has been displayed.
Function to perform the string matching in the autocomplete