fix for backward compatibility of Boundary operator: use abs(tag) for query, and revert output for negative edges

Reorganization of FloatParameterOptions and CharParameterOptions (possibly without comma at the beginning); Struct is now without value

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remove OrientedBoundary and Unique2: Boundary now always returns the signed (oriented) boundary: this is what we used to do in 
the old Geo. To get valid entity numbers, just use Abs()

* modified new internal CAD APIs to always preserve the order of the entities in transformations (even across dimensions)
* refactored extrusions - the refactoring of the old Geo code is complete (the parser does not include Geo.h anymore!)
* fixed incoherence when deleting internal entities during boolean operations, after synchronzing them with GModel
* made sure we don't bind OCC entities to multiple tags

(1) No more shift/reduce conflicts with tSTRING and String__Index!!! The solution was simply to uniform the use of String__Index in parallel rules. Will do the same kind of correction for LP and RP. (2) Extension of new Struct type