Fix query styles / string suffix problem

[dw]

Related to ticket #1, need to add at least one more query style, and give much better documentation examples.

There is at least the open/closed string suffix issue, which might need reintroduction of a NUL terminator byte in the string encoding. The problem there is that a prefix search for (1, "dave") is equivalent a include=True, lo=hi=(1, "dave") search, which presently encodes to the same prefix as (1, "dave2"). That means exact lookups for nonexistent tuples would succeed when they shouldn't.

Introducing a NUL terminator solves this, but there might be a better approach entirely.

[dw]

Since iterators now support a set_exact() match mode, this ticket might be invalid. At some point the NUL byte was also added back, it again might be removed.

Trying to describe or conceptualize the NUL byte suffix problem in one go is a pain in the ass. It's incredibly subtle