Convert bot category and tags to cl-struct
Make ob:entry:set-path as a function
Move every entry methods to function.
Add html link retriever.
Add object type retriever.
Convert entry from class to struct.
Remove all defmethod

TODO: add function dispatcher.
Convert backend to struct
Add backend registration functions
Register markdown functions
Use registred backend functions
Fix backend registration
Convert ob:framework to struct
Remove dead code
Simplify ob:get
Add function to retrieve slots
Convert org class to struct.
Make org struct site look like in eieio
Remove superfluous function self parameters
Remove eieio declarations