Seek() shouldn't return true when past maxt. Also add some tests to s…

[free]

Seek() shouldn't return true when past maxt. Also add some tests to show that Querier.Select() may return series with no values.

Signed-off-by: Alin Sinpalean alin.sinpalean@gmail.com

[free]

Was trying to add a SeekBefore() to find the first value before time t (which is what Seek() should do by default, I believe) and found a number of problems with the Seek() implementation.

This is one of the problems. The other is that Seek() will actually seek backwards within the same chunk which is (1) broken (even though never relied upon AFAICT) and (2) inefficient because it will start scanning from the beginning of the chunk. I'll address that separately.

[free]

Damned DCO. Closing because I forgot to add the signature to one of the commits.