Add information about the POS of the whole MWE

[bguil]

In case of MWE, the POS of the whole expression is not given.

For instance, below, en is ADP, particulier is ADJ but en particulier is ADV.

12	et	et	CCONJ	_	_	17	cc	_	_
13	en	en	ADP	_	_	12	advmod	_	_
14	particulier	particulier	ADJ	_	Gender=Masc|Number=Sing	13	fixed	_	_
15	à	à	ADP	_	_	17	case	_	_
16	l'	le	DET	_	Definite=Def|Number=Sing|PronType=Art	17	det	_	SpaceAfter=No
17	inspecteur	inspecteur	NOUN	_	Gender=Masc|Number=Sing	9	conj	_	_

There is not standard in UD for this.

This problem is mentioned here.
I propose to follow UD_Portuguese treebank and to use the MISC column for this. For instance :

7	,	,	PUNCT	PU|@PU	_	6	punct	_	_
8	por	por	ADP	PRP|@<ADVL	_	6	cc	_	MWE=por_exemplo|MWEPOS=CCONJ
9	exemplo	exemplo	NOUN	N|M|S|@P<	Gender=Masc|Number=Sing	8	fixed	_	SpaceAfter=No
10	,	,	PUNCT	PU|@PU	_	15	punct	_	_

And then, for en particulier, we would have:

12	et	et	CCONJ	_	_	17	cc	_	_
13	en	en	ADP	_	_	12	advmod	_	MWE=en_particulier|MWEPOS=ADV
14	particulier	particulier	ADJ	_	Gender=Masc|Number=Sing	13	fixed	_	_
15	à	à	ADP	_	_	17	case	_	_
16	l'	le	DET	_	Definite=Def|Number=Sing|PronType=Art	17	det	_	SpaceAfter=No
17	inspecteur	inspecteur	NOUN	_	Gender=Masc|Number=Sing	9	conj	_	_