Add language substitution for swedish (#37)

This adds a language substitution for & and @ in swedish.

Catch iso639-1 and iso639-3 language codes (#33)

* Format code with gofumports

* Catch also ISO 639-1 and ISO 639-3 lang codes

Added Turkish substitutions (#30)

Trim underscore at the beginning and the end (#26)

Fix #25

Order all languages alphabetically in code

Update greek language substitution to include solvents and more (#24)

We use solvents(gr: διαλυτικά) when in a word there is a vowel of two varieties, which is not pronounced as one.

The new validations are for empty string, _- as prefix or sufix of the slug and MaxLength validation if setted