Haketilo

serialize and deserialize entire Response object when relaying fetch() calls to other contexts using sendMessage

don't double-modify response headers retrieved from cache

fix application of default blocking rule under Chromium

fix chromium synchronous policy fetching for file:/// URLs

fix incorrect variable reference

prepend all generated console messages with 'Haketilo:'

change store names and data keys to singular

restore chromium support

make resource dependency specifier an object

adapt to changes in file path format

From now on we assume Hydrilla serves file contents at 'file/sha256/' instead of 'file/sha256-'.
With this commit we also stop using the "hash_key" property internally.