HTML5.1 refactor and cleanup

Recently I merged in a significant structural (but non-normative) change to the HTML5.1 master spec from the feature/whatwg branch [1]. This change actually took the form of a series of commits [2] and cleanup fixes [3] that Steve has been graciously helping me with.

Because of the nature of the change (most paragraphs in the source were reformatted to be slightly wider), the GitHub diff will appear to be too large to display. Here is a general summary of what has changed:

1. Split "Extensibility" section into 2 parts
               Before: Section 2.2.3 (Conformance requirements)
               After: Section 1.7.3 (Design notes) has bullet list of HTML-sanctioned extensibility mechanisms;
               Section 2.2.3 (Conformance) has prose about vendor prefixes

2. Moved "Interactions with XPath and XSLT"
              Before: Section 3.3 (Semantics)
              After:  Section 2.2.4 (Conformance requirements)

3. Rearranged Elements sections 3.2.4 - 3.2.6
               Before: Global attributes  > Element definitions > Content models
               After: Element definitions > Content models      > Global attributes

4. Moved "Dynamic markup insertion" section
               Before: Section 3.4 (Elements)
               After:  Section 7.3 (Web application APIs)

5. Moved "Scripting" section within Section 4 (The elements of HTML)
               Before: Section 4.3 (between "Document metadata" and "Sections")
               After:  Section 4.12 (between "Interactive elements" and "Common idioms without dedicated elements")

6. Moved "The canvas element" section
               Before: Section 4.8.11 (Embedded content)
               After:  Section 4.12.4 (Scripting)

7. Moved "Links" section
               Before: Section 4.12 (between "Interactive elements" and "Common idioms")
               After:  Section 4.8 (between "Embedded content" and "Tabular data")

8. Moved "fieldset" and "legend" sections
               Before: Between "form" and "label" (as sections 4.10.3 and 4.10.4)
               After: After "meter" (as sections 4.10.16 and 4.10.17)

9. Moved Web workers (not published in W3C spec)
               Before: Section 9 (between "User interaction" and "Communication")
               After:  Section 16 (between Channel messaging and Web storage)

. . . please reply back with any comments or concerns.

Thanks,
Erika

[1] https://github.com/w3c/html/commit/4ca5b4dfc03e0a7b2c761c6e74a73c405f6ba7ef
[2]
https://github.com/w3c/html/commit/4ca5b4dfc03e0a7b2c761c6e74a73c405f6ba7ef
https://github.com/w3c/html/commit/8c66d1fe8d6916d9aa828022841a7da627a664c3
https://github.com/w3c/html/commit/8c66d1fe8d6916d9aa828022841a7da627a664c3
[3]
https://github.com/w3c/html/commit/1f88432a184543fd0621d9e34c23225ea534e2a7
https://github.com/w3c/html/commit/fcd92cd02803e3a1939a8b18e64c40e4149fbb13
https://github.com/w3c/html/commit/450185e45fde0f23d00b5d97ad500d5fdc50b76b
https://github.com/w3c/html/commit/985415ccc0d5ae13c0acc61d0dcbf3e50112c01e
https://github.com/w3c/html/commit/ce2083cd848ccaaaff4e7a64291ac5da82664aa8
https://github.com/w3c/html/commit/f7c8d85565923d4139c062fa8f4c54fa67bb4827
https://github.com/w3c/html/commit/fec541404b16d887aacf9db8206140a2f8c632f8
https://github.com/w3c/html/commit/bbb2ff0fdcf994ea323972be167f875bee3b024e
https://github.com/w3c/html/commit/6d4638377febf3a620bb32f27640906812c2c029
https://github.com/w3c/html/commit/05417968e0c19424f69ab0232d58e1b543fc47f8