Read only values in Field

[VeckoTheGecko]

Lets make the following read only (so that users don't try to edit it expecting it to propagate to the grid

Parcels/parcels/field.py

Lines 192 to 197 in 93cc635

	# self.lon, self.lat, self.depth and self.time are not used any more in parcels.
	# self.grid should be used instead.
	# Those variables are still defined for backwards compatibility with users codes.
	self.lon = self.grid.lon
	self.lat = self.grid.lat
	self.depth = self.grid.depth

cc: @sruehs

[erikvansebille]

In fact, we could even deprecate the field.lon, field.lat and field.depth attributes; I left them in for backward compatibility when we moved to a GridSet structure back in v2.0. So it's really old, redundant code that's there just for convenience.

[VeckoTheGecko]

Yes, thats also a possibility. Let's save this particular discussion for down the line where I review all attributes/methods and suggest actions to take (deprecate to make private, make read only, etc)

[VeckoTheGecko]

Done in #1709