Rename `read` to `raw_value`

[tannewt]

read is a property but the name is a verb (aka action). Only function names should include verbs. The read property should be raw_uv, raw_value or similar nouns.

[ladyada]

@sommersoft heya i think you propertified this code, did you want to unpropertify?

[caternuson]

Fixed by #8