Report query timing and reliability in the R client, bump to 1.4.9000

- bump the version to the dev version 1.4.9000
- measure the client-side duration of every API request and report it
  as a queryDuration column (and in the verbose log)
- warn when the server cut a search short (timeExceeded) or when a
  request failed, instead of silently returning 0 counts
- disable the curl low-speed abort, which kills transfers with less
  than 1 byte/s after 600s regardless of the request timeout

Change-Id: I841e928ce07e56b00ad794022343044595f0db47
diff --git a/man/frequencyQuery-KorAPConnection-method.Rd b/man/frequencyQuery-KorAPConnection-method.Rd
index 5ae060a..33458bc 100644
--- a/man/frequencyQuery-KorAPConnection-method.Rd
+++ b/man/frequencyQuery-KorAPConnection-method.Rd
@@ -36,6 +36,7 @@
 \item \strong{query}: the query string used for the frequency analysis.
 \item \strong{totalResults}: absolute frequency of query matches in the vc.
 \item \strong{vc}:  virtual corpus used for the query.
+\item \strong{queryDuration}: client-side duration of the request in seconds.
 \item \strong{webUIRequestUrl}: URL of the corresponding web UI request with respect to query and vc.
 \item \strong{total}: total number of words in vc.
 \item \strong{f}:  relative frequency of query matches in the vc.