add msvc2019 and ditch msvc2015

CI/before_script.msvc.sh

@@ -247,7 +247,7 @@ if [ -z $CONFIGURATION ]; then
 fi
 
 if [ -z $VS_VERSION ]; then
-	VS_VERSION="2013"
+	VS_VERSION="2017"
 fi
 
 case $VS_VERSION in
@@ -507,10 +507,10 @@ fi
 		add_cmake_opts -DBoost_COMPILER="-${TOOLSET}"
 		echo Done.
 	else
-		# Appveyor unstable has all the boost we need already
+		# Appveyor has all the boost we need already
 		BOOST_SDK="c:/Libraries/boost_${BOOST_VER_URL}"
 
-		if [ $MSVC_REAL_VER -eq 15 ]; then
+		if [ $MSVC_REAL_VER -ge 15 ]; then
 			LIB_SUFFIX="1"
 		else
 			LIB_SUFFIX="0"

appveyor.yml

@@ -8,13 +8,10 @@ branches:
 
 environment:
     matrix:
-        - msvc: 2015
-          APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
         - msvc: 2017
           APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-matrix:
+        - msvc: 2019
-    allow_failures:
+          APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
-        - msvc: 2015
 
 platform:
 #   - Win32