Lower test iteration counts

Else we run into test timeouts.
Copy the std::set-based set to StdSet

It might be handy for benchmarks or tests later on.
Hash function prototypes
An empty ProbeSet wrapper
Implement ProbeSet using std::set
Strip the current temporary CuckooSet implementation
Initialize and free the internal ProbeSet table
Initialize the_size to 0
Add a custom LockGuard implementation
Add contains_nolock()
Add an early release to LockGuard
Initial work on put()
The remove() function
Update the_size on each add and remove

We might want to investigate whether to use some other,
non-central-bottleneck mechanism for size().
Add a way to retrieve the first ProbeSet element
Implement relocate()
Implement resize()
Add hash function bodies
Fill in contains_nolock()
Two comments about (potential) errors

The current code has an issue that sometimes results in double-frees,
segfaults during new and new[] operators, and similar artifacts.
The cause is not yet clear.