SpectralSequences v1.1: switched to Complexes

[mahrud]

This PR updates the SpectralSequences package to use Complexes. I noticed that #3807 and previous attempts had several bugs (e.g. conversion from truncate to naiveTruncation and the indices in the y-filtration were wrong), so I started from scratch.

• updated helpers in SpectralSequences
  • this commit also deletes various ChainComplex methods that were implemented in SpectralSequences but are now implemented by Complexes
  • it also renames truncate(Complex,ZZ) to naiveTruncation(Complex,ZZ).
• updated methods in SpectralSequences
• fixed the filteredComplex(List) constructor
• fixed the filteredComplex(Complex) constructor
• updated docs in SpectralSequences
• updated tests in SpectralSequences
• fixed an indexing bug in SpectralSequences
  • min/max behave differently for Complex and ChainComplex and are used in three different places which could cause inconsistencies if there were hidden assumptions in the past. This is worth a review.

Future things to do:

• split the file in an auxiliary directory
• trim the documentation; several nodes are 95% duplicates, and some nodes are so huge that the whole documentation is about 12MB!