docfx

1. Improve docfx init
   1. Fix #145
2. Fix multi-threading issue when applying template
3. Fix list behavior in markdown syntax to be consistent with GFM

1. Add 3 options to build subcommand:
   1. --rawModelOutputFolder: to specify the output folder for raw model if --exportRawModel. If the value is not set, raw model will be in the same folder as the output documenation.
   2. --viewModelOutputFolder: to specify the output folder for view model if --exportViewModel. If the value is not set, view model will be in the same folder as the output documenation.
   3. --dryRun: if this option is set, docfx will go through all the build processes for all the documents, however, no documentation will generated.
2. Improve markdown:
   1. Allow paired parentheses in link target, e.g. [text](paired(parentheses(are)supported)now "title").
3. Improve performance for document build.
4. Breaking changes:
   1. modify interface @Microsoft.DocAsCode.Plugins.IDocumentBuildStep.

1. Cross-reference related:

   1. Make @uid rule more strict: if @ is not followed by ' or ", it must be followed by word character ([a-zA-Z])

   2. Introduce new syntax for cross-reference:

      1. similar to autolink: <xref:uid>
      2. similar to link: [title](xref:uid) or [title](@uid)

   3. support uid in toc.yml:

      - uid: getting-started
      - uid: manual
      

   4. support cross reference in toc.md

      # <xref:getting-started>
      # [Override title](@getting-started)
      

2. Update yaml serializion:
   Add @Microsoft.DocAsCode.YamlSerialization.ExtensibleMemberAttribute
3. Improve docfx init, now with docfx init, a docfx_project seed project will will generated.
4. Several improvements for default template:
   1. Provide properties to customize layout: _disableNavbar, _disableBreadcrumb, _disableToc, _disableAffix, _disableContribution, _disableFooter
   2. Include empty main.css and main.js to head.tmpl.partial partial template so that there is no need to customize head.tmpl.partial when you want to customize website style.

1. Fix cross domain issue: timeout exception throws when document build takes longer than 15 minutes
2. Fix docfx IOException when calling docfx -l report.txt

FIX Github pages compatibility issue( Github pages now disallow iframe, however the default template of docfx uses iframe to load side toc): Update default template to use AJAX to load side toc, the original one is renamed to iframe.html. So now we have 2 embedded template, one is default and another is iframe.html.

1. docfx improvements
   1. Add subcommand docfx template. You can now docfx template list and docfx template export -A to list and export all the embeded templates!
   2. Add subcommand docfx merge. You can use this subcommand to merge platform from multiple APIs with the same uid
   3. Add two options to build subcommand, --exportRawModel and --exportViewModel. --exportRawModel exports the data model to apply templates, --exportViewModel exports the view model after running template's pre-process scripts.
   4. Add --globalMetadata, and --globalMetadataFile options to build subcommand. These options allow globalMetadata to be loaded from command line in json format or from a JSON file.
   5. Add --fileMetadataFile option to build subcommand. This option allows fileMeatdata to be read from an external JSON file.
   6. Support plugins. You can create your own template with a plugins folder, inside which, you create your own build steps. Refer to @Microsoft.DocAsCode.EntityModel.Plugins.BaseDocumentBuildStep for a sample plugin implementation.
2. DFM syntax improvements
   1. Support note&div syntax
   2. Support query format in code snippet
      [!code-<language>[<name>](<codepath><queryoption><queryoptionvalue> "<title>")]
   3. Change xref logic:
      1. If content after @ is wrapped by ' or ", it contains any character including white space
      2. If content after @ is not wrapped by ' or ", it ends when:
         1. line ends
         2. meets whitespaces
         3. line ends with ., ,, ;, :, !, ? and ~
         4. meets 2 times or more ., ,, ;, :, !, ? and ~
3. Code improvements
   1. Add @Microsoft.DocAsCode.YamlSerialization
      This project is based on YamlDotNet. It overrides classes like type converters to improve performance and fix bug existed in YamlDotNet
   2. Refactor markdown engine @Microsoft.DocAsCode.MarkdownLite
   3. Add @Microsoft.DocAsCode.MarkdownLite.IMarkdownRewritable`1. It provides a way to operate markdown tokens.
4. Other improvements
   1. Add a new property _path into _attrs, it stands for the relative path from docfx.json to current file
   2. Improve missing xref warning message to include containing files.
   3. Add data-uid as attribute to generated html from default template, so that you can now find uid for API much more easily.