Modifications to the Ranges chapter as a partial implementation of the edits from the spec review on 4/19/2011 also: - reflected informal communications with Brad - introduced the "represented sequence" property - other fixes
Modifications to the Ranges chapter as a partial implementation of the edits from the spec review on 4/19/2011
also:
- reflected informal communications with Brad
- introduced the "represented sequence" property
- other fixes

Details:

* Defined a range as a set of 4 properties: low, high, stride, alignment.
  Low/high can be infinities. Alignment can be "ambiguous".

* Introduced these 4 properties plus defined other properties used throughout
  the chapter (aligned bounds, first/last, naturally aligned, etc.)
  in the first section of the chapter.

* Also introduced the "represented sequence" term/property
  (the sequence of ints given by the range)
  as the name for the range's informal semantics/value.

* Eliminated the use of the term "field", using "property" instead.
  (This has the unintended side-effect that we are not forced
  to discuss their in-place updating, as we would for "fields".)

* Reworked the presentation of the range types, values and a few operations,
  relying on the previously-introduced properties and organizing them
  according to the conventions we have for the spec.
  E.g. sorted the predefined functions in each subsection.

* Removed the definition of natural alignment and isNaturallyAligned().
  We can reintroduce these if we need to (e.g. when defining
  how a range is printed with writeln(), but we should discuss
  the definition first.

* Minor semantic fixes where the wording did not match the intention.

* Sprinkled REVIEW comments. Renamed TODOs and NOTEs to REVIEWs.


git-svn-id: 88467cb1fb04b8a755be7e1ee1026be4190196ef@18757 3a8e244f-b0f2-452b-bcba-4c88e055c3ca

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