Luaparser

What's Changed
* `Statement` node is now a descendant of `Expression` node

Fixes
* Missing brackets on table 26
* Nested unary expressions 27
* Comments in the end of Node will be skipped 28
* Fail to reject unassigned global variable declaration 29
* Fail to reject an invalid escape sequence 30

What's Changed
* Fix lua ouput indenter by penguinol in https://github.com/boolangery/py-lua-parser/pull/25
* Feature/support pickling nodes by ypaliy-vdoo in https://github.com/boolangery/py-lua-parser/pull/20


**Full Changelog**: https://github.com/boolangery/py-lua-parser/compare/3.1.0...3.1.1

New feature

* each node now contains line infomation and start/stop token

python
class Node:
"""Base class for AST node."""
comments: Comments
first_token: Optional[Token]
last_token: Optional[Token]
start_char: Optional[int]
stop_char: Optional[int]
line: Optional[int]

Bug fixes

* fix 11: no visitor found for class StringDelimiter
* fix xml printer

Breaking changes

Index node
Index.idx use now a Name node instead of a String node:
Before: Index(idx=**String('a')**, value=Name('x'))
Now: Index(idx=**Name('a')**, value=Name('x'))

New features

* Index node: add notation property:

python
index_node.notation

class IndexNotation(Enum):
DOT = 0 obj.foo
SQUARE = 1 obj[foo]


* String node: add delimiter information

python
string_node.delimiter

class StringDelimiter(Enum):
SINGLE_QUOTE = 0 'foo'
DOUBLE_QUOTE = 1 "foo"
DOUBLE_SQUARE = 2 [[foo]]


* add a lua source printer

Fixes

* cant walk the ast tree in some cases.
* Merge pull request 7 from NanakiPL/master
* named an unnamed exception
* tests: add lua printer tests.