Add support for second language

[barsv]

Adds support for recording speech in two languages using separate hotkeys.

Configuration

UTTERTYPE_LANGUAGE="en"                              # Primary language
UTTERTYPE_SECOND_LANGUAGE="ru"                       # Secondary language
UTTERTYPE_RECORD_HOTKEYS="<ctrl>+<alt>+v"           # Primary hotkey
UTTERTYPE_RECORD_HOTKEYS_SECOND_LANGUAGE="<ctrl>+<alt>+r"  # Secondary hotkey

[dhruvyad]

Thanks for contributing to uttertype! Left some comments regarding style and some doc updates.