Add `Memory.intersect_*(other)`

[TexZK]

Iterates over the common stuff between a memory and something else.

• intersect_keys(): iterates over common addresses, one by one.
• intersect_values(): iterates over common values, one by one.
• intersect_items(): iterates over common key and value pairs, one by one.
• intersect_intervals(): iterates over common intervals.
• intersect_gaps(): iterates over common gaps.
• intersect_blocks(): iterates over common blocks.

More: add & and &= operators to work like intersect_items() (API closer to dict's operator |).
(TODO: Open dedicated issue tickets)