Explorer: More robust configurable pattern selection

[lukasrothenberger]

          more advanced and with some boilerplate code all around, but potentially more stable:

use a map (string->function) that has all the supported types and their run_.... functions.
the parser should then query the available suggestion types for the documentation string and validation.

this way, when we add more patterns, we know that the documentation stays up to date.

Originally posted by @goerlibe in #447 (comment)