unable to collapse Joint Filters
Hello.
I'm using Pandas' pyTables functionality to select rows from a moderate-sized table on disk (< 300,000,000 rows).  However, it raises the exception:
`NotImplementedError: unable to collapse Joint Filters`
when I try to do something like:
`store.select('Trans','(ID == 998) & (TillID==13)')`
(where store is an open instance of pandas.io.pytables.HDFStore)

Until that functionality is implemented, does anyone know if there is a way to work-around it? - perhaps via the underlying PyTables implementation of something similar?

In case it is relevant, I'm executing `pandas.computation.expressions.set_use_numexpr(False)`

near the start of my application to avoid the crashing issue mentioned in #6720 

I'm not familiar enough with the source to be able propose a fix myself at this time.

Thanks!
