Unify colour in settings and language

[Jeremy Hopkins]

This is a simple language question. In UK you say colour and americans say color. But in development we always use color. So I changed the english language labels to colour and the moodle variables to color. Probably all of them were my fault.

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best to use color everywhwere to avoid confusion.

[Info 3bits]

As en language, colour must be used. If the lang file is translated to en-us or other version, then could be changed to color.

[Info 3bits]

Fix #56

→ <<cset 81208bebd037>>

[Info 3bits]

Fix #56

→ <<cset 81208bebd037>>