Version 3.5.1

Added unit test for multiply_plain_inplace when plain is a monomial.

Faster validity checks in evaluator for _plain operations' plaintext

inputs

Fix running unit tests in Mac

Update NuGet package metadata to be compliant

Updated Changes.md

Minor edits to documentation.

Minor updates to Changes.md and CKKSENcoder.cs

Changed version to 3.2.2

Added test to verify bug in multiply_many