Add feature to enable/disable collection of Inference trails(Fcstat) in URE

[amebel]

Presently collection of inference trails is enabled by default. For creation of simple-english wikipedia or other atomese datasets, for use with the present chatbot, the collection of these trails isn't required. Having the option to disable them should help in squeezing in some more content into ram. There might be other performance benefits as well.

scheme@(guile-user)> (use-modules (opencog) (opencog atom-types) (opencog nlp) (opencog nlp chatbot) (opencog nlp relex2logic))
scheme@(guile-user)> (length (cog-get-trunk (Concept "dummy-source")))
$1 = 0
scheme@(guile-user)> (nlp-parse "This is the first test.")
$2 = ((SentenceNode "sentence@6f27c907-be77-47f2-97ba-ba6d4952fc0a")
)
scheme@(guile-user)> (length (cog-get-trunk (Concept "dummy-source")))
$3 = 7
scheme@(guile-user)> (nlp-parse "This is the second test.")
$4 = ((SentenceNode "sentence@56d6687a-3cec-4cb9-8547-43f4b61ff2ae")
)
scheme@(guile-user)> (length (cog-get-trunk (Concept "dummy-source")))
$5 = 14
scheme@(guile-user)> (nlp-parse "The quick brown fox jumped over the lazy dog, so they say or not.")                              
$6 = ((SentenceNode "sentence@d4182948-9d4c-4a6b-ba34-ef2080e4a6ee")
)
scheme@(guile-user)> (length (cog-get-trunk (Concept "dummy-source")))
$7 = 27
)

[ngeiswei]

@amebel do you still care about that? Since the forward chainer code is eventually gonna be merged with the backward chainer, I would rather not bother, but let me know.

[amebel]

@ngeiswei I don't have an immediate need, but it would be nice to have that feature in the merged chainers version of URE.

[ngeiswei]

OK. The BC offers that (basically if no trace atomspace is provided it doesn't record anything). Since merging FC/BC will be forked from the BC, we can assume it will be there. But just as a remainder I'll let this issue open.

[ngeiswei]

Fixed, one can use option #:trace-as in cog-fc, see (help cog-fc).