[ts-gen] limits in risk.rb

[Bill Pippin]

Nils,

I've just pushed another release that blocks db inserts together.
This is an initial step to:

    o maintaining an internal, matching image of the db journal;

    o checking candidate inserts for equality with existing records;

    o and building internal data structures to reflect open orders

    o which would allow: cross-session order manipulation.

I'll be looking at the problem with decimals next week; I suspect
you've found a problem that needs to be fixed, and I'll let you
know what I find.  Thanks very much for this report.

The shim updates the portfolio values table even at startup because
the tws sends portfolio value records at that time if your account
isn't flat.

The very last release from last Friday, as well as the one pushed
tonight, now allow nulls in the OrderResult (portfolio value) and
OrderReport tables.

Though I've gone back and forth on this, I believe this is, on
balance, the right choice at least for the current api client
version, so possibly null ibc values should remain acceptable for
the forseeable future.

With either of these last two releases, and an updated database to
provide the revised attribute declarations, you should no longer see
the transient insert error messages.

Thanks,

Bill