BUG/MEDIUM: map: The map parser includes blank lines.

The parser check the end line comparing to the null character.
In fact, the end of line can be also '\r' or '\n'.

The effect is that empty lines are loaded and indexed in maps.

The bug was introduced by commit d5f624dd ("MEDIUM: sample:
add the "map" converter") in 1.5-dev20. No backport is needed.