* 2115 IP
* Initial implementation of Expression node
* Register Expression Node
* Add Expression DocumentNode Definition
* DocumentNodeImplementation::Expresssion in guess_type_from_node
* Move expression.rs to graphene-core
* WIP: Investigating 'exposed' & 'value_source' params for Expression property
* Node graph render debug IP
* Single input can change node properties; complex debug IP
* Fix epsilon in test
* Handle invalid expressions in expression_node by returning 0.0
* Run cargo fmt
* Set the default expression to "1 + 1"
* Hardcode the A and B inputs at Keavon's request
* Rename and clean up UX
* Move into ops.rs
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Co-authored-by: hypercube <0hypercube@gmail.com>
Co-authored-by: Keavon Chambers <keavon@keavon.com>