Need to fix numeric field overflow error when used custom miltiplier for the item.

When using custom multiplier for the item with type "numeric" sometimes can appear "numeric field overflow" error in the zabbix log file:

3286:20100102:155134.118 [Z3005] Query failed: [0] PGRES_FATAL_ERROR:ERROR: numeric field overflow
DETAIL: A field with precision 16, scale 4 must round to an absolute value less than 10^12.
[insert into history (itemid,clock,value) values (503490,1262436691,100000000000000.000000);

Seems that this problem appears because Zabbix is checking these values before applying custom multiplier.

Also there is problem with "trends" table:

20100104:203307.681 [Z3005] Query failed: [0] PGRES_FATAL_ERROR:ERROR: numeric field overflow
DETAIL: A field with precision 16, scale 4 must round to an absolute value less than 10^12.
[insert into trends (itemid,clock,num,value_min,value_avg,value_max) values (18440,1262624400,395,13287.000000,24934.210738,42752.800000);