HTTP_1.1_REQUIRED

Adds a "1.1 Required" error code, and a mention of the error code in the Renegotiation section.  Hopefully addresses #496.
Fixing name, adding to IANA section
Merge pull request #625 from http2/http11req

 HTTP_1.1_REQUIRED
a HTTP -> an HTTP
Merge pull request #628 from npcode/fix/a-http

a HTTP -> an HTTP
fix broken line ends
fix broken xref (which needed to be an x:ref)
"send a client data" -> "send data to a client"

Rational: "a client data" can be misparser.  Con: "data" gets further from the
relative clause "that" referring to it.
"any place" -> "in any place" twice.
"any place that" -> "any place where" twice.
"so that" -> "in such a fashion"

Otherwise it is not clear whether it is the sole act of defining the initial
value that results in the extension initially disabled.
Rewording "That is, a sequence...".

The original sentence "That is, a sequence..." did not have a verb.
Reword "is must".

One too many verbs in the original sentence.
Merge pull request #630 from bencebeky/master

Proposed editorial changes to make the draft more precise or easier to read.
Tiny editorial changes
Fix bit numbering

Bits seem to be numbered from 1 to N, which is very confusing since
almost every software starts at zero. Also it's common to find macros
like :

  #define BIT(N) (1 << (N))

and here that would introduce mistakes since one constantly has to
think about shifting bits before using the macro (eg: BIT(3) to check
bit called "4" in the spec, corresponding to value 0x8).

Since there are not that many places where this happens, this commit
aims at fixing them. Note that the hexadecimal values for each of them
were already correct and non-ambiguous.
Merge pull request #631 from wtarreau/fix-bit-numbering

Number bits starting from zero
Permitting receipt of WINDOW_UPDATE in reserved (local)
update rfc2629.xslt
Merge pull request #635 from http2/wurl

Permitting receipt of WINDOW_UPDATE in reserved (local)