Current Behavior

The useTsconfigDeclarationDir in typescript2 rollup plugin is set to false.

Desired Behavior

When declarationDir is set in tsconfig.json set useTsconfigDeclarationDir to true.

Suggested Solution

useTsconfigDeclarationDir: tsconfigJSON && tsconfigJSON.declarationDir

Who does this impact? Who is this for?

This would fix #135 and in general improve experience in Monorepos (making "Go To Definition" work).

Describe alternatives you've considered

Using tsdx.config.js but the config is not easy to change and it's needed in every package of the monorepo.