Split multi-line translation strings into single line translations

[NathanLovato]

The translation strings currently take strings from the content blocks as-is but it makes it more difficult to make and update translations. It gives extra work to translators (multiplied by content updates and languages).

We need to split blocks into single-line translations instead.

Tasks:

• Split the lines from the content blocks when extracting strings
• Split content block lines when populating lessons, practices, etc., and call the tr() function on each line.
• Use a script to merge all existing translations into the new translation file structure