Release 2.1.0

About ASN1 release 2.1.0:

1. The functionality and API is the same as in the previous release

2. Apple has removed the function

   swift package generate-xcodeproj

   in Xcode 14.3. This means that it is no longer possible to generate a Swift Package
   and then turn it into an Xcode project, in order to define testability.

   Since there is now no Xcode project where testability can be enabled, the line

   @testable import ASN1

   must be inserted in every test file, in order to still be able to run the testsuite.
   This has been done in release 2.1.0

   The testsuite must be run in release mode, otherwise it takes forever.
   This can be done from the command line with

   swift test -c release -Xswiftc -enable-testing

   The above considerations are only relevant for the development of ASN1,
   not for people who just use ASN1.