AppVeyor and infra updates

- Change build image to VS 2019
- Update Microsoft.SourceLink.GitHub package
- Update solution file
- Build separate symbol package (.snupkg)

S7.Net/S7.Net.csproj

@@ -15,14 +15,17 @@
     <RepositoryType>git</RepositoryType>
     <PackageTags>PLC Siemens Communication S7</PackageTags>
     <Copyright>Derek Heiser 2015</Copyright>
+    <DebugType>portable</DebugType>
+    <EmbedAllSources>true</EmbedAllSources>
+    <IncludeSymbols>true</IncludeSymbols>
+    <SymbolPackageFormat>snupkg</SymbolPackageFormat>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(TargetFramework)' == 'net452' Or '$(TargetFramework)' == 'netstandard2.0' ">
     <DefineConstants>NET_FULL</DefineConstants>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0-beta-62925-02" PrivateAssets="All" />
-    <PackageReference Include="SourceLink.Copy.PdbFiles" Version="2.8.3" PrivateAssets="All" />
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
   </ItemGroup>
 </Project>

S7.sln

@@ -1,16 +1,17 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio 15
-VisualStudioVersion = 15.0.27703.2026
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.29806.167
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "S7.Net", "S7.Net\S7.Net.csproj", "{BFD484F9-3F04-42A2-BF2A-60A189A25DCF}"
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{7A8252C3-E6AE-435A-809D-4413C06E0711}"
 	ProjectSection(SolutionItems) = preProject
+		appveyor.yml = appveyor.yml
 		README.md = README.md
 	EndProjectSection
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "S7.Net.UnitTest", "S7.Net.UnitTest\S7.Net.UnitTest.csproj", "{303CCED6-9ABC-4899-A509-743341AAA804}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "S7.Net.UnitTest", "S7.Net.UnitTest\S7.Net.UnitTest.csproj", "{303CCED6-9ABC-4899-A509-743341AAA804}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution

appveyor.yml

@@ -1,13 +1,13 @@
-image: Visual Studio 2017
+image: Visual Studio 2019
 configuration: Release
 install:
   - choco install gitversion.portable -y
 before_build:
   - cmd: gitversion /l console /output buildserver
-  - nuget restore
+  - dotnet restore
 build_script:
   msbuild /nologo /v:m /p:AssemblyVersion=%GitVersion_AssemblySemVer% /p:FileVersion=%GitVersion_MajorMinorPatch% /p:InformationalVersion=%GitVersion_InformationalVersion% /p:Configuration=%CONFIGURATION% S7.sln
 after_build:
-  - dotnet pack S7.Net -c %CONFIGURATION% /p:Version=%GitVersion_NuGetVersion% --no-build -o ..\artifacts
+  - dotnet pack S7.Net -c %CONFIGURATION% /p:Version=%GitVersion_NuGetVersion% --no-build -o artifacts
 artifacts:
   - path: artifacts\*.*