Initial support for closure codegen

SPEC_FORMAT.md

case_studies/tests/src/closures.rs

case_studies/tests/src/lib.rs

case_studies/tests/src/mixed.rs

case_studies/tests/src/references.rs

case_studies/tests/src/traits.rs

rr_frontend/radium/src/code.rs

rr_frontend/radium/src/specs.rs

rr_frontend/translation/src/base.rs

...rontend/translation/src/environment/dump_borrowck_info.rs

rr_frontend/translation/src/environment/polonius_info.rs

rr_frontend/translation/src/environment/procedure.rs

rr_frontend/translation/src/function_body.rs

rr_frontend/translation/src/lib.rs

...nslation/src/spec_parsers/verbose_function_spec_parser.rs

rr_frontend/translation/src/traits.rs

rr_frontend/translation/src/type_translator.rs

theories/lithium/syntax.v

theories/rust_typing/automation.v

theories/rust_typing/closures.v