The previous definition could result in unexpected errors.
The previous oneof(...) throws an instantiation error
when the parsed term is not ground. This may happen for example
when a JSON object is parsed to a dict (tag is a variable).
The replacement has the same semantical meaning but avoids
throwing an instantiation exception when applied on a dict.

New source directory is src/ with web_api components in src/web_api/.

Closes #38

Closes #41

Inlined occurs check

Closes 35

Created predicate retracting all items into theory_bg.

closes 21

closes 29

Updated comments

Unneccessary thanks to module types