Merge remote-tracking branch 'origin/master' into ralf/prophecy

.gitlab-ci.yml

CHANGELOG.md

README.md

theories/bi/derived_laws_bi.v

theories/heap_lang/lang.v

theories/heap_lang/lifting.v

theories/heap_lang/notation.v

theories/heap_lang/proofmode.v

theories/program_logic/ectx_language.v

theories/program_logic/language.v

theories/program_logic/lifting.v

theories/program_logic/total_lifting.v