file begins with a number, but is not a number (e.g. "132x52"), return the
specified default enum value - not the index of the last enum value. This fixes
the issue with unregonized/supported syncterm.ini and syncterm.lst screen mode
values causing the last screen mode (ATARI XEP80) to be used.

You can still specify a numeric enum value, but it has to be the entire value
(white-space separated comments are still supported).

Hex (and octal!) numbers are still supported for enum values, no special code
needed: strtoul() handles that for us.

iniReadEnumList and iniGetEnumList now use 0 as the default value (instead of
highest enum value).