9.0.0: Drop PHP 5 support

• Implemented xp-framework/rfc#334: Drop PHP 5.6. The minimum required
  PHP version is now 7.0.0!
  (@thekid)

8.0.4: XP10 compatibility

• Made compatible with XP 10 - @thekid

8.0.3: PHP 7.4 compatibility

• Added PHP 7.4 compatibility - @thekid
• Increased test coverage to 100% - @thekid

8.0.2: PHP 7.2 compatiblity fix

• Fixed PHP 7.2 compatibility - @thekid

8.0.1: Void return type fix

• Fixed each() and peek() not being able to work with functions
  with void return type.
  (@thekid)

8.0.0: XP9 Compatibility

• Merged PR #45: Forward compatibility with XP 9.0.0 - @thekid

7.0.1: Test code QA

• Refactored code to use dedicated fixture methods instead of using
  xp class methods typeOf() and gc(), see xp-framework/rfc#323
  (@thekid)

7.0.0: Remove deprecated functionality

• Merged PR #43 ("Remove deprecated functionality"):
  . Removed Sequence::concat() method deprecated in favor of a multi-
  argument version of Sequence::of() - see 6.4.2-RELEASE
  . Removed deprecated classes from yield refactoring released in 6.4.1
  (@thekid)

6.6.0: Lazy evaluation in of()

• Added support for closures returning iterables in Enumeration::of()
  (@thekid)

6.5.1: Small performance improvement

• Improved each() performance when passing extra arguments - @thekid