Improve lookup heuristic

[eagleflo]

~ % jisho ある限り
~ % jisho "all (there is)"
ある限り【あるかぎり】- all (there is), as long as there is

That's not ideal. The original very naïve piece of code just looked at the first character of the input when deciding which HashMap to look from. I rewrote it so that if there is any 漢字 in the query we look at keb rather than reb. Likewise reading lookups now require the whole input to be in 仮名; according to JMdict DTD reb is restricted to 仮名.

[eagleflo]

Fixed in 9c3fe27.