convert: allow tags detection to be disabled
Tags calculation becomes more reliable but slower, measurable on frequent
synchronizations.
convert: follow svn tags history (
issue953)
convert: avoid svn log retrieval process cleanup
With huge history (like kdelibs), the process termination suddenly consumes a
lot of memory (from 700M to 1.3G+). Since the job is done, clean termination is
not required, just exit.