Use a value_pair_tmpl_t in xlat_exp to store details of the attribute ref
Make mismatch message readable
Remove another dynamically allocated vpt
Modify dict_attrbytagged_name to update src string pointer
':' is not a valid dictionary name character

Add row/column headers to dict_attr_allowed_chars
Add tmpl_afrom_attr_substr and tmpl_from_attr_substr

These functions advance the name pointer to the end of the parsed portion of the string