add_enum_member

add a member of enum - a symbolic constant
     enum_id - id of enum
     name    - name of symbolic constant. Must be unique
               in the program.
     value   - value of symbolic constant.
     bmask   - bitmask of the constant
               ordinary enums accept only -1 as a bitmask
               all bits set in value should be set in bmask too
returns: 0-ok, otherwise error code CONST_ERROR_...

long add_enum_member(long enum_id, string name, long value, long bmask);

#define CONST_ERROR_NAME  1     // already have member with this name (bad name)
#define CONST_ERROR_VALUE 2     // already have member with this value
#define CONST_ERROR_ENUM  3     // bad enum id
#define CONST_ERROR_MASK  4     // bad bmask
#define CONST_ERROR_ILLV  5     // bad bmask and value combination (~bmask & value != 0)