Preemptive changes in preparation for the WHATWG cherry-pick of "The great clean-up of 2013" in attempts to make the merge more sane. This change implements the following structural changes from that commit:

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)
Another preemptive change in preparation for the WHATWG cherry-pick of "The great clean-up of 2013": Replacing title="" attributes with data-x="" for elements (for all except 44 specific occurrences in example code).
[e] (0) The giant clean-up of 2013. Improved internal consistency, adjusted section order to make more sense, started a move away from abusing title='' for cross-references, fixed minor typos, cleaned up some dangling TODOs, very minor typo fixes, dropped some obsolete comments, un-commented-out minor things that had previously been commented out for reasons that no longer apply, etc. No normative changes.
Affected topics: CSS, Canvas, DOM APIs, HTML, HTML Syntax and Parsing, Microdata, Offline Web Applications, Rendering, Security, Video Text Tracks, Video and Audio, WebSocket API, Workers

git-svn-id: http://svn.whatwg.org/webapps@8229 340c8d12-0b0e-0410-8428-c7bf67bfef74

W3C editorial note: Added several missing FORK markers, and also a two new ones for a couple of normative changes in this commit regarding conformance checkers using the microformats wiki and MetaExtensions wiki (WHATWG version now says "must use", W3C still says "may use").