1116 Add options param to unparsed-text

[michaelhkay]

Reverts the change to unparsed-text and unparsed-text-lines so they no longer normalise line endings by default.

Instead an options parameter is added to select this as a non-default behaviour.

At the same time, we add an option to control whether the function is deterministic (that is, returns the same content if called repeatedly with the same URI). In 3.1 the spec stated that implementations might provide an option to do this, but did not provide an interoperable way of setting this option. For compatibility, the default is still to be deterministic.

Fix #1116