[Qgis-developer] Add all geometry predicates in "XXX by location" processing algorithms

[Arnaud Morvan]

We want to make a pull request on this processing geoalgorithms:
"Select by location", "Extract by location" and "Join by location".

In "Select by location", we have actually three boolean parameters :
- Include input features that touch the selection features
- Include input features that overlap/cross the selection features
- Include input features completely within the selection features
treated in an boolean "or" combination.

Effective treatment depends on type of geometries :
   If layer to select from is a point layer : result = A.intersects(B)
   If one the two layers is a line layer : overlap/cross <=> A.crosses(B)
                                                   else : overlap/cross 
<=> A.overlap(B)

We want to propose all standard predicates to the user :
contains, crosses, disjoins, equals, intersects, overlaps, touches, within

Apparently we could not disable some parameter checkboxes based on 
geometry types without overiding the default generated dialog.

Note : For the disjoins predicate, we have to skip the spatial index filter.

Does anybody have some remarks/objections on this.

Arnaud