Add py-pyPEG2.

I am currently in the process of creating ports for various components
related to CloudABI, including ARPC (an RPC framework that supports file
descriptor passing) and Flower (a capability-based network backplane).

The former comes with a script called 'aprotoc' for creating C++
bindings for messages and RPC services. This script depends on Python's
pyPEG2 package to parse (a subset of) Protobuf's .proto grammar.

Reviewed by:	wg
Differential Revision:	https://reviews.freebsd.org/D12048

textproc/Makefile

@@ -1305,6 +1305,7 @@
     SUBDIR += py-parsimonious
     SUBDIR += py-pdfminer
     SUBDIR += py-pss
+    SUBDIR += py-pyPEG2
     SUBDIR += py-pyctpp2
     SUBDIR += py-pyelasticsearch
     SUBDIR += py-pyes

textproc/py-pyPEG2/Makefile

@@ -0,0 +1,20 @@
+# Created by: Ed Schouten <ed@FreeBSD.org>
+# $FreeBSD$
+
+PORTNAME=	pyPEG2
+PORTVERSION=	2.15.2
+CATEGORIES=	textproc python
+MASTER_SITES=	CHEESESHOP
+PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
+
+MAINTAINER=	ed@FreeBSD.org
+COMMENT=	Parsing Expression Grammar (PEG) parser for Python
+
+LICENSE=	GPLv2+
+LICENSE_FILE=	${WRKSRC}/LICENSE.txt
+
+USES?=		python
+USE_PYTHON=	autoplist distutils
+NO_ARCH=	yes
+
+.include <bsd.port.mk>

textproc/py-pyPEG2/distinfo

@@ -0,0 +1,3 @@
+TIMESTAMP = 1502893061
+SHA256 (pyPEG2-2.15.2.tar.gz) = 2b2d4f80d8e1a9370b2a91f4a25f4abf7f69b85c8da84cd23ec36451958a1f6d
+SIZE (pyPEG2-2.15.2.tar.gz) = 40334

textproc/py-pyPEG2/pkg-descr

@@ -0,0 +1,7 @@
+PyPEG2 is a parser-interpreter for Parsing Expression Grammars (PEGs).
+
+PEGs look similar to context-free grammars (CFGs), except that the choice
+operator always picks the first matching option. This allows for parsing
+in linear time.
+
+WWW: https://fdik.org/pyPEG/