On branch master

Hello Dalibor!

Thank you for this gem. I was planning to implement similar functionality for an Uzbek texts, so I added a conversion table for that language.

I was wondering if you could implement one functionality for me?
The Cyrillic letter "е" (in Uzbek and Russian) is transcribed as "ye" if it start a word and is substituted by a single letter "e" if it is not the first letter in a word. There is a separate letter "э" in case the first sound is similar to Latin "e".

For example: 
  етим: yetim
  телефон: telefon
  этап: etap

Thanks anyways and have a good day!

Bobirkhon Ismailov

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Changes to be committed:
In Russian alphabet add letter 'Э'
	modified:   lib/alphabets/russian.yml

Add Uzbek alphabet
	new file:   lib/alphabets/uzbek.yml