Adding support for JMustache compiler customization

[regga-ws]

Extension of the CodegenConfig interface in order to use JMustache compiler native features, such as the deactivation of HTML escaping.

My custom generator implements it like this :

@Override
public Compiler processCompiler(Compiler compiler) {
   return compiler.escapeHTML(false);
}

[wing328]

Re:

@Override
public Compiler processCompiler(Compiler compiler) {
   return compiler.escapeHTML(false);
}

Thanks for the PR. Can you please elaborate on why you want to turn off escapeHTML?

[regga-ws]

With escapeHTML turned on by default, special characters such as simple or double quotes will be transformed into their HTML code (respectively ' and ") by the compiler. In my case, I am using a custom codegen generator to transform descriptions from a swagger spec into an human-readable document, and I end up with visible sentences such as :

...following attributes can't be updated...
...possible values are 'ABP'...

Also, I believe that other compiler configuration features may be interesting for some developers, for example to customize delimiters in some cases.

[wing328]

@regga-ws the change sounds reasonable to me. If you want the tag without escaping HTML special characters, you can also use {{{tag_name}}} instead of {{tag_name}}