[Yaml-core] Changes to folding mechanism and elimination of "quoted strings"

[Clark C . E. <cc...@cl...>]

Earlier I had thought that RFC822 forced condensation of 
consecutive white spaces into a single space like HTML.  
Since I was only 1/2 right (true for structured headers)
and since the 1/2 that I was right about matters little 
to us, this requires some re-thinking.  Furthermore, I've
been unhappy about the "quoted  string" thingy.  Yucko.
Therefore, below is the new scalar value proposal.

...

There are three syntax forms for scalar values, 
"block", "stream", and "mime" which are used to
accomidate differing needs for expressing content.
The block form specializes in pre-formatted or
raw text, the stream form works well for 
unformatted content, the mime form is ideal 
for binary values or very large chunks of 
formatted text.

In the block form:
  a) trailing whitespace is significant
  b) end of line marker is also significant
  c) there is not a quoting or escaping mechanism
  d) each line must begin with the block symbol,
     which is currently "|"
  e) a slash character can be used in place 
     of the block symbol for the very last
     line to indicate that the block does not
     terminate with an end-of-line marker.

In the stream form:
  a) leading/trailing whitespace is not significant
  b) the end of line marker is also not significant
  c) consecutive whitespaces bounded by printable
     characters are significant
  d) standard slash style \n, \t, \\ style
     escaping is provided
  e) a trailing slash is used to indicate that
     the last character of a line and the first
     character of the next line are ajacent 
     without an intermediate space

In the mime form:
  a) the entire content is included as a seperate
     MIME section and may be transfer-encoded
     using base64 or quoted-printable
  b) the content is assigned an identifier
  c) this identifier can be used to provide
     a reference to the content within the 
     YAML proper

Examples of the block form include:

  a: | This line does not need \ escaping.

  b: 
  |This is a block form
  |with two end of line markers.

  c: |
     |     X
     |    X X
     |   X X X
     |
     | This one has a leading
     | carriage return and
     | does not have a trailing
     \ end of line marker.

Examples of stream form include:

  a: This is a simple one liner
  b: This has     intermediate spaces.
  c: This is a multi line
     value that wraps\taround and\n
     uses an end of line marker.
  d:
   \n      X
   \n     X X
   \n    X X X
   \n
   \n This one is just like "c" above.
   \n Except that \\ escaping is required.


An example of the mime form is...


Date: Sun, 13 May 2001 23:48:04 -0400
MIME-Version: 1.0
Content-Type: multipart/related; 
    boundary="================================"
X-YAML-Version: 1.0

--================================
Content-Type: text/plain; id="0001"

  XX XXX    XXXXX   XX   XX
   XXX XX       X   XX X XX
   XX      XXXXXX   XX X XX
   XX      X   XX   XXXXXXX
  XXXX     XXXXX X   XX XX

--================================
Content-Type: text/x-yaml

  raw: *(0001)

--================================--