Change progress indicator to status bar.

Along with this commit come a few changes in the console, mostly color-related.
One new behavior: hitting ENTER no longer escapes the follow mode. You need to
do this either with ESC or 'q'.

An invalid query syntax still produces an ugly libcppa error. This will be
fixed soon.
Correctly report result count for empty results.

If a partition will not produce a single index hit, it has to indicate this.
Previously partitions silently dropped this case, causing the index processing
to not report 100% although the query already completed.