Expr\List will now contain ArrayItems instead of plain variables.
I'm reusing ArrayItem, because code handling list() must also handle
arrays, and this allows both to go through the same code path.
This also renames Expr\List->vars to ->items.
TODO: Should Expr\List be dropped in favor of Expr\Array with an
extra flag?
Scalar\String_ and Scalar\Encapsed now have an additional "kind"
attribute, which may be one of:
* String_::KIND_SINGLE_QUOTED
* String_::KIND_DOUBLE_QUOTED
* String_::KIND_NOWDOC
* String_::KIND_HEREDOC
Additionally, if the string kind is one of the latter two, an
attribute "docLabel" is provided, which contains the doc string
label (STR in <<<STR) that was originally used.
The pretty printer will try to take the original kind of the string,
as well as the used doc string label into account.
To distinguish array() and [] syntax. The pretty printer respects
this attribute. The shortArraySyntax pretty printer option acts as
a default in case the attribute is not specified.
We can't strip the <?php at the end of a __halt_compiler() segment
in file mode.
Fixed by being a bit more explicit in prettyPrintFile() about what
we want to do...
