5.1.2: Promotion of by-reference parameters fix

• Fixed promotion for by-reference arguments - @thekid

5.1.1: Operator precedence fix

• Fixed ternary and instanceof operators' precedence - @thekid

5.1.0: PHP 8 syntax adoptions

• Merged PR #82: Allow chaining scope resolution operator :: - @thekid
• Merged PR #81: Allow instanceof (<expr>) as syntax - @thekid
• Merged PR #80: Allow new (<expr>) as syntax - @thekid

5.0.0: Drop PHP5

• Merged PR #70: Extract compact methods; to use these, require the
  library https://github.com/xp-lang/php-compact-methods
  (@thekid)
• Merged PR #79: Convert testsuite to baseless tests - @thekid
• Merged PR #78: Deprecate curly brace syntax for offsets; consistent
  with PHP 7.4
  (@thekid)
• Added support for XP 10 and newer versions of library dependencies
  (@thekid)
• Implemented xp-framework/rfc#334: Drop PHP 5.6. The minimum required
  PHP version is now 7.0.0!
  (@thekid)

4.3.1: XP10 compatiblity

• Added compatibility with XP 10, see xp-framework/rfc#333 - @thekid

4.3.0: Hashtag comments

• Fixed global constants in ternaries being ambiguous with goto labels
  (@thekid)
• Fixed emitting switch statements and case labels' ambiguity w/ goto
  (@thekid)
• Fixed an operator precedence problem causing incorrect nesting in the
  parsed AST for unary prefix operators.
  (@thekid)
• Merged PR #77: Add support for #-style comments including support for
  XP style annotations
  (@thekid)

4.2.1: Abstract and final types fix

• Fixed parser to allow "extending" final and abstract types - @thekid

4.2.0: Ast subcommand

• Fixed issue #74: No longer shadow compiler errors in certain cases
  (@thekid)
• Merged PR #75: Add "ast" subcommand to display the abstract syntax tree
  (@thekid)

4.1.0: Annotations in anonymous classes

• Merged PR #73: Add support for annotations in anonymous classes
  (@thekid)

4.0.0: Syntax plugins

• Merged PR #69: Remove support for Hack arrow functions - @thekid
• Fixed operator precedence for unary prefix operators - @thekid
• Merged PR #66: Syntax plugins. With this facility in place, the compiler
  can be extended much like Babel.
  This is useful for adapting features which may or may not make it into
  PHP one day. Current extensions like compact methods are kept for BC
  reasons, but will be extracted into their own libraries in the future!
  (@thekid)