optiq-csv date types

[Martijn van den Broek]

Hi Julian,

I am not sure if you got a notice but I created this pull request on the optiq-csv repo:

https://github.com/julianhyde/optiq-csv/pull/5

We started trying to get the connection.getMetaData() to return the correct datatype for the date columns. This lead to the changes in convert() which seemed to be necessary to convert to the correct date format. All tests still pass and I added an additional one.

I hope these changes are ready to go to master. Else let us know and we can try to make them better. Nice work on the optiq stuff btw.