Changes to allow changes to dimension values in ASR data entry.

Modify packages P_STATISTIC and P_STATISTIC_GROUPS to allow updating of dimension values.

Modify package P_ASR to use the new P_STATISTIC and P_STATISTIC_GROUPS facilities.

Add new procedure DELETE_ASR_ROW to allow deletion of all data associated with a row in
any ASR table, by simply specifying the primary statistic group identifier. This will
probably replace the individual delete procedures for each ASR table, although the existing
procedures have not yet been removed from the package.

Add an index on T_STATISTIC.STG_ID_PRIMARY to make the general ASR row deletion facility
more efficient.

Modify ASR data load scripts to cater for the new parameter arrangement for procedure
P_STATISTIC.INSERT_STATISTIC.