petascope clip should check intersection properly with coverage's subset

[Bang Pham Huu]

Currently, petascope check if each vertex inside poylgon clipping must be inside coverage's subset. However, it is incorrect as 1 polygon can intersect with a subset and the result is the intersection between 2 objects.

The check is valid only if 2 objects don't have any intersection.

Example query with intersection:

for c in (mean_summer_airtemp) return encode( 
clip(c[Lat(-28.6492:-16.8856), Long(128.8483:136.5387)],
POLYGON((-21.3273 128.8483, -16.8856 136.5387, -25.0429 145.4596, -28.6492 134.7370, -21.3273 128.8483)))
, "png")

Error returns

Coordinate value '145.4596' is not valid. Reason: Coordinate is not within domain [128.825:136.575] of axis 'Lon'.