Functionality from fda

We should provide the functionality offered by the R fda package. The following is the list of functionalities provided in the fda package, their implementation status and how are they implemented.

Functions

Function (fda)	Status	Function (Python)	Missing
AmpPhaseDecomp	Unimplemented
argvalsy.swap	Unnecesary
arithmetic.basisfd	Review	Overload equality operator
arithmetic.fd	Review	Overload several operators
as.array3	Unnecesary
as.fd	Partial	FDataBasis constructor	Construct from spline objects
as.POSIXct1970	Unnecesary
axisIntervals	Unnecesary
basisfd.product	Review	Overload of multiplication OR new function
bifd	Unimplemented	FDataBasis constructor	Support for multiple dimensions
bifdPar	Unnecesary	The functions should accept a list of parameters instead
bsplinepen