Update to the Estonian TTS configuration

* "Bear ..." ("hoidke ...") now uses adessive case (alalütlev, "on ...") instead of elative (seestütlev, "from ...");
* spelt-out "maantee", "puiestee" and "allee" are now recognized as types of streets and declined accordingly;
* in time announcements there is now a "ja" ("and") between hours and minutes;
* in time announcements there was a bug that said essentially "5 hours **0 minutes**"; *it might be good to fix this in the rest of the languages too*;
* tidied up some comments;
* compactified the code by reusing decline_string;
* made several functions give unique answers by using the Prolog "cut" operator ("!"): this avoids nasty surprises, makes the code run more efficiently and simplifies debugging.