Allow Algorithm param to be comma-delimited list for PassphraseHash and randomly select one from list.

[boughtonp]

When hashing, accept a comma-delimited list for Algorithm and randomly select which one to use.

Setting Algorithm to "random" should be equivalent to listing all implemented algorithms (excluding any known to be insecure).

This makes it easier for applications to use multiple algorithms, limiting the potential impact if a flaw is found in any particular algorithm.

TBD is how to handle AlgorithmParams - all keys in one struct (requires the params to be exclusive), or as array/struct containing a struct per algorithm.