Statically store computational security parameter

[jot2re]

We are currently passing around many security parameters. Of these, one specific is a symmetric crypto security parameter. However, this parameter should be directly defined by the concrete encryption/hash functions used. I think it would be better to remove this as a parameter and let it be located as a final variable with the hash/encryption objects used instead.

[jot2re]

This can be implemented with a global static and final hash map where variables can be added and accesses on demand

[jot2re]

Many SPDZ and SPDZ2k subprotocols require a statistical security parameter. Currently it is set statically in BasicNumericContext. However, we want to handle this in a nice way. It should instead be on the resource pool where it can be loaded either from a command line argument, or file, or as a fall-back a default value (e.g. 40 or 60).

[jot2re]

This should ideally be handled by a class which sets up the default values, and sanity checks when new values are added. E.g. as is needed in #288