Support typedoc.json "extends"

[DennisJaamann]

Add support for creating extended typedoc.json files.

This functionality already exists for:

• TypeScript configs
• TsLint configs

So why not do the same for typedoc when we want for example a company wide configuration for typedocs with the same theme etc preconfigured.

Example:

node_modules/@somecompany/somelib/typedoc.json

{
  "mode": "file",
  "module": "commonjs",
  "theme": "default",
  "out": "docs",
  "target": "ES5",
  "moduleResolution": "node",
  "includeDeclarations":"false",
  "ignoreCompilerErrors": "true",
  "experimentalDecorators": "true",
  "externalPattern":"**/*.d.ts",
  "excludeExternals":"true",
  "emitDecoratorMetadata": "true",
  "preserveConstEnums": "true",
  "stripInternal": "true",
  "suppressExcessPropertyErrors": "true",
  "suppressImplicitAnyIndexErrors": "true"
}

someprojectusingsomelib/typedoc.json

{
  "extends": "@somecompany/somelib/typedoc.json"
}

Currently, there is a way of achieving this but it feels rather cumbersome / not community standard in comparison with tools such as typescript or tslint.

 "scripts": {
    "docs": "npm run typedoc -- --options node_modules/@somecompany/somelib/typedoc.json ./src/",
    "typedoc": "typedoc"
  },

[aciccarello]

Cool idea. PRs welcome.