Cannot have "0" as XProfile field option

[johnjamesjacoby]

If you try to create an XProfile field option with the name "0" the following error will occur:

'This field type requires at least one option. Please add options below.'

[johnjamesjacoby]

​6443.01.patch uses isset() rather than empty() in BP_XProfile_Field::admin_validate().

[johnjamesjacoby]

Same goes for fields; they cannot be named "0" due to an empty() check in the same method.

[johnjamesjacoby]

In 9878:

XProfile: Add tests for "0" field names and field options. See #6443.

[johnjamesjacoby]

In 9879:

XProfile: Improve field validation in BP_Profile_Field::admin_validate().

• Break inline conditions apart into multiple specific ones to improve logical flow of field validation
• Introduce more helpful $message feedback for each new condition, including the field-type name where possible
• Replace empty() checks with ! isset() to allow "0" values as names and options
• Remove field_file check, as the "file" field type was removed when avatar uploads were refactored in 1.0
• Much more appropriate field-option validation using sanitize_text_field to
• Properly escape gettext output
• Tests introduced in r9878

See #6443.

[johnjamesjacoby]

This is complete.