Undelete User; if User code exists appends /n to User code

When undeleting a User, if the original code now exists, finPOWER Connect will append ".n" to the User code - where "n" is a number starting from 1.

For example, if you delete User "A" finPOWER Connect will update its code to something like "123~A" (123 is the User's Primary Key). You can then add a User with a code of "A". If you now attempt to undelete User "123~A" (originally "A") finPOWER Connect will see there is now a User with that code and will instead use "A.1".

Previously finPOWER Connect changed the code to "_n", i.e. using an underscore. However, underscore is not allowed to be used in codes - hence this caused an issue.