spatch/pretty: fix pretty printer for encaps, e.g. $o = "this is $bar encaps"

Summary: zejiac needs that for #1981026

Test Plan:
unit test included
make test

Reviewers: julienv, pieter

Reviewed By: julienv

CC: zejiac

Differential Revision: https://phabricator.fb.com/D729026

Task ID: 1981026
pfff: support (new Foo)->bar() (part 1)

Summary:
This is mostly a copy paste of the zend patch
https://github.com/php/php-src/commit/eebaaf423f98fa0340038e4350a82b97d738a355

Test Plan:
unit test included
make test

Reviewers: pieter, ptarjan, amenghra, julienv

Reviewed By: pieter

Differential Revision: https://phabricator.fb.com/D729567

Task ID: 2152233
pfff: support (new Foo)->bar() (part 2)

Summary: Collateral evolutions because of the new NewLv constructor.

Test Plan:
unit test included
make test

Reviewers: pieter, ptarjan, amenghra, julienv

Reviewed By: pieter

Differential Revision: https://phabricator.fb.com/D729569

Task ID: 2152233