pginstaller - pginst: * Move user creation to execute sequence * Means

Log Message:
-----------
* Move user creation to execute sequence
* Means we now support user creation during silent install (but not with random password)
* Validate user account during silent install
* While around there, fix the problem reported where SERVICEDOMAIN specified on the commandline is ignored
* Remove all direct access to MsgBox and SendErrorMessage from user.c and sspi.c, and use error buffers instead. So the
samefunction can be used from both UI and execute sequence. 

Modified Files:
--------------
    pginst/ca:
        pginstca.c (r1.83 -> r1.84)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/pginst/ca/pginstca.c.diff?r1=1.83&r2=1.84)
        pginstca.h (r1.6 -> r1.7)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/pginst/ca/pginstca.h.diff?r1=1.6&r2=1.7)
        sspi.c (r1.5 -> r1.6)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/pginst/ca/sspi.c.diff?r1=1.5&r2=1.6)
        user.c (r1.18 -> r1.19)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/pginst/ca/user.c.diff?r1=1.18&r2=1.19)
    pginst/wxs:
        pginst.wxs (r1.138 -> r1.139)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/pginst/wxs/pginst.wxs.diff?r1=1.138&r2=1.139)