Code documentation, some tweaks and bugfixes.

.npmignore

examples/behaviortree.html

examples/chain.html

examples/creature.html

examples/index.html

examples/lecture1/creature.ts

examples/lecture1/rectangles.ts

examples/lecture1/text.ts

examples/lecture2.html

examples/lecture2/lecture2.ts

examples/lecture3.html

examples/lecture3/constants.ts

examples/lecture3/example1.ts

examples/lecture3/example2.ts

examples/lecture3/example3.ts

examples/lecture3/example4.ts

examples/lecture3/main.ts

examples/lecture4.html

examples/lecture4/Integrations.ts

examples/lecture4/Matter.ts