Terra-layer

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* Update source layer by layer pk and not by name

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* Fix missing property on interactions

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* Command to replace the source of the layer

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* Filter NULL value on discretize method

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* Add missing display and config field properties

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* Add import file process only if load_xls command exists
* Add way to specify selectors when inserting in tree
* Fix boundaries when no data
* Allow to provide manual boundaries for graduated
* Fix circle size legend
* Add default style on field less layer
* Implement auto legend for Proportional Symbol
* Add mapbox gl style generator