Update master from 5.x

[weirdan]

• Process @psalm-this-out on __construct() as well
• Report first class callables generated for unknown static methods
• Handle taking references to unspecified magic methods
• Report invalid number of arguments for psalm-taint-*
• fix test
• Use IssueBuffer::maybeAdd() instead of throwing
• Improve randomizer stubs
• Improve parsing of psalm-type
• Allow multiple spaces between type name and type definition