Epic: Replace template engine

[RicoSuter]

Missing feature: Compile template at runtime... so that templates can be customized on a per template basis

In the future, we will use DotLiquid as template engine in NSwag and NJsonSchema to support template customizations, etc.

Documentation: https://github.com/RSuter/NSwag/wiki/Templates
Also see https://github.com/NSwag/NSwag/wiki/Roadmap

Implications:

• The template model classes are part of the public API and must be stable after this changes (because people start to customize parts of the templates which are coupled to the model classes).

[RicoSuter]

Ref: RicoSuter/NJsonSchema#404

[RicoSuter]

RicoSuter/NJsonSchema#515

[RicoSuter]

T4 to Liquid regexes:

<#=Model.(.*?)#>
{{ $1 }}

<#=(.*?)#>
{{ $1 }}

<#(.*?)#>
{% $1 -%}

[RicoSuter]

https://github.com/RSuter/NJsonSchema/wiki/Templates

[RicoSuter]

Notepad++ language for liquid:

liquid_notepadpp.zip

[RicoSuter]

Documentation https://github.com/RSuter/NJsonSchema/wiki/Templates