dict_col_t::is_virtual() - replaces dict_col_is_virtual,
    dict_col_t::copy_type(type) - replaces dict_col_copy_type
    dict_col_t::get_mbminlen() - replaces dict_col_get_mbminlen
    dict_col_t::get_mbmaxlen() - replaces dict_col_get_mbmaxlen
    dict_col_t::set_mbinmaxlen(mbminlen, mbmaxlen) - replaces dict_col_set_mbminmaxlen

Remove dict_field_get_col(field) method - using field->col instead.

RB#13498
Reviewed by Kevin Lewis