Add search box to language selection dialog on Symbian

[vitalii17]

The selection dialog will be more usable if you add area for quick search of language. You may use sortfilterproxymodel class for this purposes:

https://github.com/Vitalii17/Streets/blob/master/Streets/src/sortfilterproxymodel.h https://github.com/Vitalii17/Streets/blob/master/Streets/src/sortfilterproxymodel.cpp