Fix bug when a channel is empty.
Merge pull request #183 from samuelgarcia/spike2io_bug_182

This close the issue #182
fixed indentation bug in read_block that caused only one site to be returned
Merge pull request #184 from mschachter/tdtio_singlesite_fix

fixed tdtio problem where only one site in a tank was being read
Merge remote-tracking branch 'upstream/master' into develop