Name::$parts array is replaced by Name::$name string.

Previously it was only part of NodeAbstract.

Not that the interface makes much sense anyway, but these are
implementation details of a specific traverser.

Add ErrorHandler interface, as well as ErrorHandler\Throwing
and ErrorHandler\Collecting. The error handler is passed to
Parser::parse(). This supersedes the throwOnError option.

NameResolver now accepts an ErrorHandler in the ctor.

The NameResolver now adds a namespacedName attribute on function/
const names which cannot be statically resolved.

Nearly all special errors are now handled gracefully, i.e. the
parser will be able to continue after encountering them. In some
cases the associated error range has been improved using the new
end attribute stack.

To achieve this the error handling code has been moved out of the
node constructors and into special methods in the parser.

Lexer::startLexing() no longer throws, instead errors can be fetched
using Lexer::getErrors().

Lexer errors now also contain full line and position information.

These were necessary back in the day when we had to emulate some
complex functionality such as nowdoc strings. Now we can simply
directly translate certain token sequences.

The motivation for this change is to avoid preprocessing of the source
code, which would complicate offset-aware error handling inside the
lexer as offsets would no longer be correct.

These have been superseded by Error::(get|set)StartLine().

Conflicts:
	CHANGELOG.md

This adds support for void, iterable and nullable types.

Conflicts:
	lib/PhpParser/Parser/Php7.php

Exposes the properties and adds an additional nodeType property.