WordEditView: Fix the theme of selected letter

JCombobox was not showing right theme of currently selected letter.
Fix it.
model: Fix editing of letter associated with word

Pass the new letter to the model otherwise model otherwise model will asssume
first character to be letter word is associated with.
model: Fix search box

- Hook model into search box.
- Fix model functions to match right string
Merge pull request #32 from CS673/vivek-model-fixes-4

Vivek model fixes 4