Basic infrastructure for machine translation services
Configuration for machine translation
Test for basic machine translation operations

Implemented using dummy translation class
Implement basic JSON request method
MyMemory backend for machine translation
Move URL construction to base class
Another layer for JSON requests (some do not need status code checking)
Initial support for Open-Tran (issue #128)
Add missing docs
There is no need to manually set service id
Correctly use MT ID attribute
Add language code conversion layer
Implement language code conversions
Initial Glosbe support (issue #135)