- Improve the error handling according to Jelmer's suggestions
- Print out the error messages on "stderr"
- Add also here the "choice" type for arguments

I removed it since on some scripts it was present, on others not - so I thought
it wouldn't be really needed. This was a bad decision (pointed out by abartlet).
So I reintroduce it on all scripts (to have consistent parameters).

- I removed also the "-H" parameter since those scripts are all thought for the
  use on a local s4 domain controller. Another reason is also the bind as SYSTEM
  account which itself is only possible on local binds.

Validate that each field is within its allowed range.  Also validate that the
maximum password age is greater than the minimum password length (if the maximum
password age is set).

I could not find these values documented anywhere in the WSPP docs.  I used the
values shown in the W2K8 GPMC, as it appears that the GPMC actuaally performs
the validation of values.

If we cannot retrieve the value, do not assume a particular value.  The fact
that we could not retrieve the value indicates a larger problem that we don't
want to make worse bypossibly clearing bit fields in the pwdProperties
attribute.