Improvements to meta guide
First chapter is done
Add chapter about agents
GenServer chapter is done
Supervisors and Applications
Event manager chapter is done
Don't use rest_for_one strategy
ETS chapter
No catch-all for handle_info
Revert "No catch-all for handle_info"

This reverts commit a32db6794d439a5d04c195db6713e4fc99a9d197.
Start migrating to KV
KV-fied chapter 3
KV-fied chapter 4 and 5
All chapters reviewed to distributed KV
Talk about mix test --trace
Add dependencies chapter
Task and gen_tcp
Start laying out new structure
Initial work on chapter 9
Get rid of unecessary on_exit callbacks