introduced new addon system. use ./src/addons/simple-addon.component.ts as reference. Do not compile old addons - they won't work.
Now there is no need to compile DSW with addon. Addon can be used in different build of DSW.
added addon versioning support, checks and warning if inappropriate addon version loaded in DSW
added detailed addons documentation Addons.md
added detailed addon example code with comments
now addon builder produces correct and same names for addon files my-addon.ts > my-addon.js (previously, Angular CLI creates addon-0, addon-1, etc.)
now, after addition of new services to base widget class, there is no need to recompile and redeploy all addons