Beta release v0.8.8 (with updated UI)

Fixes to allow (1) disabling of 'use_cache' across releases which may share works (previously, shared works left incomplete look-ups if use_cache was disabled) and (2) works which might appear in their own right and also have arrangements. Also, re-set certain important options to defaults on starting Picard, namely: 'use_cache' set to True, 'log_debug', 'log_info' and 'options_overwrite' set to False; the user will need to deliberately re-set these on starting Picard if required - this is to prevent inadvertently leaving these flags in an abnormal state.
Subject to any bugs and code-tidying, this is intended to form the next pull request.
EDIT 29/12/17: The UI in classical_extras.zip (not the source files) has been updated to allow scrolling and use with smaller screens.