reachableTerms function is ill-defined

[hartig]

The reachableTerms function is defined only informally. The recursive nature that this informal definition seems to imply is problematic as mentioned in a comment on PR #350.

The function is used in two places:

1. within the ALP_recurse function
2. in the definition of the Evaluation of OneOrMorePath

Notice that the function was called 'eval' in SPARQL 1.1, where it is used in the same two places (see the ALP function in 1.1 and the definition of OneOrMorePath in 1.1).

[afs]

"by repeated matches of path."

That could be "all matches" it is grounded by the fix x.