A special case that requires filter over TokenList id

For the following example,

# sent_id = reviews-002288-0001
# newpar id = reviews-002288-p0001
# text = It's well cool. :)
1-2	It's	_	_	_	_	_	_	_	_
1	It	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	4	nsubj	4:nsubj	_
2	's	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	cop	4:cop	_
3	well	well	ADV	RB	Degree=Pos	4	advmod	4:advmod	_
4	cool	cool	ADJ	JJ	Degree=Pos	0	root	0:root	SpaceAfter=No
5	.	.	PUNCT	.	_	4	punct	4:punct	_
6	:)	:)	SYM	NFP	_	4	discourse	4:discourse	_

The parsed result will be

TokenList<It's, It, 's, well, cool, ., :)>

[{'id': (1, '-', 2),
  'form': "It's",
  'lemma': '_',
  'upos': '_',
  'xpos': None,
  'feats': None,
  'head': None,
  'deprel': '_',
  'deps': None,
  'misc': None},
 {'id': 1,
  'form': 'It',
  'lemma': 'it',
  'upos': 'PRON',
  'xpos': 'PRP',
  'feats': {'Case': 'Nom',
   'Gender': 'Neut',
   'Number': 'Sing',
   'Person': '3',
   'PronType': 'Prs'},
  'head': 4,
  'deprel': 'nsubj',
  'deps': [('nsubj', 4)],
  'misc': None},
]

The parsing has no problem. However, in some cases, one may want to use those id that is integer.

How about make TokenList to support filter those with only integer id? Like this

sentence.filter(id=lambda x: type(x) is int)

[Vimos]

I grouped them into lambda_basic and lambda_deep, the test cases are also simplified.

[EmilStenstrom]

I added a brief section about filtering by lambda in the README, and just released conllu==4.3 that supports this. Thanks for your contribution!