Feature Request: Check for legal characters in SNMP configuration

[cs1]

I'm using

2.2.6-RELEASE (amd64)
built on Mon Dec 21 14:50:08 CST 2015
FreeBSD 10.1-RELEASE-p25

I accidentally discovered that the web-UI on the page "Services: SNMP" doesn't verify that only legal characters are used as SNMP sysLocation etc.. It would be very helpful to build a check into that page that only USASCII characters are used for SNMP fields that are of the type "DisplayString" (see https://www.ietf.org/rfc/rfc1213.txt, section 3.2). Both configurable attributes "System location" and "System contact" should be checked for legal characters (they are both of type "DisplayString" in MIB-II).