Add double, triple and quadruple primes to tab-completion

moar Unicode goodness - in the reference w3c symbol mapping file, the multiple prime symbols are mapped to `''`, `'''` etc. and not their corresponding Unicode characters and therefore have to be special-cased.

Also add reversed single, double, triple primes as well as quadruple prime to allowable jl_id_char's

cc: @JeffBezanson