White space processing and line breaking

Finish the sections on white space processing and line breaking.

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[x] Be more clear about how braille translation is affected by the white space processing rules and line breaking rules. (Currently the spec just says "... as long as in the end the white space processing, line breaking and braille translation rules are satisfied...")
The ‘white-space’ property
[ ] Do we need 'pre' or 'nowrap'?
[ ] Explain differences with original white-space propery.
White Space Processing Rules
[ ] Explain differences with original white space processing rules.
Line Breaking
[ ] What about the BK, CR, CM, NL, and SG classes (normative line breaking)? (EDIT: the Line Separator U+2028 is currently used internally in DP2 to represent preserved line breaks)
[ ] What about the WJ and BA classes (soft wrap opportunities)?
[ ] Explain differences with original line breaking rules: no prioritization, no out-of-flow elements, no replaced elements, no line-break property and no word-break property.