Add autocomplete support for camelCase predicates

[ppp225]

Currently, autocomplete works well for predicates using dot notation (i.e. movie.budget)
It would be a huge improvement for folks using ratel with camelCased predicates, if autocomplete would work with them, and possibly other casings as well.

i.e. having following predicate: movieBudget, when typing movi we get the suggestions, however when continuing typing movieB, suggestions disappear.