docfx

1. The latest csproj introduces in a new property TargetFrameworks, docfx does not support it for now. To make docfx work, please specify TargetFramework when calling docfx. A sample docfx.json would be as follows. The merge command is to merge YAML files generated with different TargetFramework into one YAML file.

{
    "metadata": [
        {
            "src": "*.csproj",
            "dest": "temp/api/netstandard1.4",
            "properties": {
                "TargetFramework": "netstandard1.4"
            }
        },
        {
            "src": "*.csproj",
            "dest": "temp/api/net46",
            "properties": {
                "TargetFramework": "net46"
            }
        }
    ],
    "merge": {
        "content": [
            {
                "files": "*.yml",
                "src": "temp/api/netstandard1.4"
            },
            {
                "files": "*.yml",
                "src": "temp/api/net46"
            }
        ],
        "fileMetadata": {
            "platform": {
                "temp/api/netstandard1.4/*.yml": [
                    "netstandard1.4"
                ],
                "temp/api/net46/*.yml": [
                    "net46"
                ]
            }
        },
        "dest": "api"
    },
    "build": {
        "content": [
            {
                "files": [
                    "api/*.yml",
                    "**.md",
                    "**/toc.yml"
                ]
            }
        ],
        "dest": "_site"
    }
}

1. Rename new markdown engine to dfm-latest and dfm-2.15.
2. add back legacy markdown engine to dfm and dfm-2.13.
   Markdown engine can be switch by command line option markdownEngineName or docfx.json, see document.

1. Markdown html should not match inline html element.

1. Fix markdown list with tab indent.
2. Support escaped pipe in table.

1. Auto dedent the included code snippet, both when including the whole file and file sections.
2. [Breaking Change]For inline inclusion, trim ending white spaces, considering ending white spaces in inline inclusion in most cases are typos.

1. Fix duplicate project references fail GetCompilationAsync. https://github.com/dotnet/docfx/issues/1414

1. Filter config file is expected in working dir instead of project's dir/src dir.
2. Create msbuild workspace with release configuration by default. https://github.com/dotnet/docfx/pull/1356