Working on supporting user operators
Fixed operator expression references
Fixed binaryoperatorExpression, updated dep to khepri-ast V4
Adding unary and binary tests for custom ops
Updating changelog
Updated for Khepri-parser V4.1
Changed binary and unary to use operator nodes instead of string values.
Updated unary to use op node too.
Fixing pres table parser for operators
Updated tests for operator nodes
Generat Operator expressions nodes
Updated tests
Removed  from being valid operator char