Complete project package I have been working on a D8 project and been wondering what the best course of action would be in order to produce a complete project package that can be easily set up in a new drupal installation. The theme part is pretty straightforward but what about all the specific content types that accompany a project with a specific theme? Is there a way I can have those being created on theme installation?
You can add the needed configuration files of the content types and fields needed for the site in a folder named config/install in your theme directory. These configuration gets imported when we install it.

for eg: if you want to create a content type test when your theme is installed

Create a file node.type.test.yml in your_theme/config/install folder paste the code in it 

langcode: en
status: true
dependencies:
  module:
    - menu_ui
third_party_settings:
  menu_ui:
    available_menus:
      - main
    parent: 'main:'
name: test
type: test
description: ''
help: ''
new_revision: true
preview_mode: 1
display_submitted: true


Easy method is to 


create the content types and fields form backend 
export the configuration
Take the newly created files from it and remove the line uuid from it
paste it in your theme folder