E eILCD as standard interface between bw_data and bw_io

[cmutel]

The current interface between bw2data and bw2io is inadequate - it does not include a lot of important metadata, it grew organically without clear design or vision, it doesn't not distinguish between inventory and impact assessment, and it barely specified and therefore impossible to implement by outside collaborators.

Specific tasks:

• E1 bw_io needs to to support the Brightway Common Database standard
• E2 Python decorator to use old-style bw_io strategies without converting internal logic to ILCD data standard

Nice-to-have:

• E3 bw_io strategies rewritten to use the ported ILCD data standard internally
• E4 Code audit of bw_io for test coverage and strategy obsolescence