marker-size as integer

[skeenp]

Add support for integer pixel size for the marker-size property. Allows implementations to allow user to specify explicit pixel sizes for markers.

// OPTIONAL: default "medium"
// specify the size of the marker. sizes
// can be different pixel sizes in different
// implementations
// Value must either an integer pixel  size or
// or one of
// "small"
// "medium"
// "large"
"marker-size": "medium",