Implement lazy loading of external libraries

[thet]

External libriaries (fullcalendar, moment, pikadate, depends_handler, etc) are loaded via dynamic imports on initialization time of the pattern. That way they are only loaded when the pattern is actually used. This reduces bundle size a lot.

There are still many testfailures - but as far as I have tested it, the demos do work.

Before:

-rw-rw-r--  1 thet thet 615K Sep 25 01:10 bundle.js
-rw-rw-r--  1 thet thet 351K Sep 25 01:10 bundle.min.js
-rw-rw-r--  1 thet thet  69K Sep 25 01:10 bundle-polyfills.js
-rw-rw-r--  1 thet thet 2.9K Sep 25 01:10 bundle-polyfills.min.js
-rw-rw-r--  1 thet thet 841K Sep 25 01:10 bundle-vendors.js
drwxrwxr-x  2 thet thet  20K Sep 25 01:10 chunks

After (Note: bundle-vendors is now combined in bundle.js):

-rw-rw-r--  1 thet thet 809K Sep 25 17:14 bundle.js
-rw-rw-r--  1 thet thet 295K Sep 25 17:14 bundle.min.js
-rw-rw-r--  1 thet thet 461K Sep 25 17:14 bundle-polyfills.js
-rw-rw-r--  1 thet thet 142K Sep 25 17:14 bundle-polyfills.min.js
drwxrwxr-x  2 thet thet  12K Sep 25 17:14 chunks

This is the output from webpack-bundle-analyzer: