Typescript refactor: Platform select for browser and node

Created by: bodograumann

This adds a new option to select the platform as node or browser. When no platform is selected, a default is chosen by the framework option and likewise the file data type option is implied by the platform.

I did not have time to overhaul the tests, so I currently left the default sample build as node version and the jquery sample build as browser, as the latter uses proper e2e tests.

This PR assumes that my previous PR is merged, so currently those commits are listed as well.

I also included some other minor improvements and fixes.

Cf. #802 (closed) CC @TiFu