Cifras o letras

There are three screens:
* The menu screen, where you can choose language (with it's own statistical letter distribution) and timeout.
* The numbers screen, where you can choose six numbers pushing units or decades and the goal is to get the closest possible to the target number using arithmetic operations.
* The letters screen, where you can choose nine letters pushing vowel or consonant and the goal is to find the largest existing word using these letters.

The game doesn't resolve any of the puzzles, it's just a random generator of numbers and letters.

# Changelog
## v1.3.1
* Made font size device dependent.
* Add scroll for small devices.
* Change game screens internal structure.
* Can set time in 30 seconds interval.
* Fixed some problems with the application context.
* Improvements in letter statistical distribution using hunspell dictionaries data.

## v1.3.0 (not released)
* Added Android TV support.
* Use of SoundPool instead of MediaPlayer. Fixed crash when ending sound plays.
* Changed RelativeLayout to ConstraintLayout.

## v1.2.2
* I