Arithmetic expressions support

What's Changed

• Add Arithmetic support by @atoledo in #244

Full Changelog: v1.5.9...v1.6.1

UPDATE: don't use release v1.6.0

v1.5.4

• Update dependencies.

v1.5.3

Fixed an issue where conditions with object data were not being simplified correctly.

v1.5.2

• Update dependencies.

v1.5.1

• Fix issue with nested conditions not being completely simplified.

v1.5.0

• Add simplify capability to strictly evaluate the expression for all referred values not present in the context except for a specified list of optional keys

v1.4.5

• Updated rollup package

v1.4.4

• Updated packages

v1.4.3

• Prevent unexpected parsing of any expression used as an operand in a comparison expression

v1.4.2

• Change @babel/env preset to > 1%, node 12.