FIP-0054: Filecoin EVM runtime (FEVM) (#569)

* initial incomplete draft for EVM compatibility FIP.

* outdent specification sections.

* split into two FIPs; WIP.

* continue fleshing out specifications; use semantic line breaks.

* continue fleshing out the Ethereum Accounts and EAM FIP.

* rename FIP file.

* stamp FIP number.

* add LOG opcodes specification.

* remove FIP-0055 from here.

* wip: major updates for completeness.

* complete draft.

* document Filecoin precompiles.

* minor edit.

* adjust event definition for LOG opcodes.

* apply method number reorganization, adopting FRC42 call convention.

* prose adjustments.

* add token_amount to InvokeContractDelegate params.

* align HandleFilecoinMethod specification with latest implementation.

* various refinements.

* further refine opcode remarks.

* re-align precompiles specification with implementation.

* update discussion link.

* document more differences between Ethereum and Filecoin EVMs.

* cover addressing stability caveat.

* regenerate ToC.

* adjust opcode definitions.

* address nits.

* address nit.

* fix actor_type definition

* remove vscode file.

* address my own feedback

(and document PUSH0)

* params are CBOR.

* elaborate on memory semantics.

* adjust GASPRICE opcode behavior.

* clearly specify that REVERT aborts.

* send::send now takes a gas_limit.

* refinements to differences with Ethereum.

Co-authored-by: Steven Allen <[email protected]>