minor release

• core helper to open databases as read-only/immutable (useful for Docker mounts)
• some cachew experiments, including cachew base directory (still work in progress)
• more stat functions and improvements for stats
• initial work on using proper virtualenv for DAL helpers (using emfit to start with)

modules affected:

• reddit
• pdfs
• bluemaestro
• emfit
• twint
• rescuetime