* Don't assign to attribute stack on reduce - why was that there
in the first place?
* Assign attributes to the position in the stack where the first
token of the production is, instead of one position earlier.
* Add a comment to clarify why we also assign attributes on read,
instead of just on shift.
Minor performance improvement for parsing, also allows to access
attributes with higher granulity in the parser, though this is not
currently done.
* #n can now be used to access the stack position of a token. $n
is the same as $this->semStack[#n]. (Post-translate $n will
actually be the stack position.)
* $attributeStack is now $this->startAttributeStack and
$endAttributes is now $this->endAttributes.
* Attributes for a node are now computed inside the individual
reduction methods, instead of being passed as a parameter.
Accessible through the attributes() macro.
The parser didn't account for the additional newline after the content of doc strings, which is left there by the tokenizer for some reason. Additoinally esacape sequences were parsed in nowdoc strings.
Additionally this contains some minor changes to the grammar: Some _list nonterminals were refactored to have the possible single elements in a reparate rule and only assemble those single elements. (This reduces duplication and gives better assignment of line number context.)
