use azure pipelines instead of appveyor for builds

* trial azure pipelines

[skip ci]

* use vs2017

* build pr commits

* include codecov and update test nuget

* add codecov call

* add publish test results step

* include coverlet package for test coverage and allow coverlet dynamic public types

* add azure pipelines badge and remove appveyor badge

* add nuget pack step

* use build configuration variable for nuget pack and move after build

* fix path to package to pack

* change nuget to dotnet pack

* remove old codecov related tools

src/CodeCoverage/CodeCoverage.cmd

@@ -1,9 +0,0 @@
-@echo off
-
-cd src\CodeCoverage
-
-nuget restore packages.config -PackagesDirectory .
-
-cd ..
-
-CodeCoverage\OpenCover.4.6.519\tools\OpenCover.Console.exe -target:"dotnet.exe" -targetargs:"test UglyToad.PdfPig.Tests\UglyToad.PdfPig.Tests.csproj  --framework netcoreapp2.0 -c debug" -register:user -output:.\test-results.xml -hideskipped:All -returntargetcode -oldStyle -filter:"+[UglyToad.PdfPig*]* -[UglyToad.PdfPig.Tests*]*" 

src/CodeCoverage/packages.config

@@ -1,4 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<packages>
-  <package id="OpenCover" version="4.6.519" />
-</packages>

src/UglyToad.PdfPig.Tests/PublicApiScannerTests.cs

@@ -1,5 +1,6 @@
 namespace UglyToad.PdfPig.Tests
 {
+    using System;
     using System.Collections.Generic;
     using System.Linq;
     using System.Reflection;
@@ -19,6 +20,12 @@
 
             foreach (var type in types)
             {
+                // Skip coverage measuring instrumentation classes.
+                if (type.FullName.StartsWith("Coverlet", StringComparison.OrdinalIgnoreCase))
+                {
+                    continue;
+                }
+
                 if (type.IsPublic)
                 {
                     publicTypeNames.Add(type.FullName);

src/UglyToad.PdfPig.Tests/UglyToad.PdfPig.Tests.csproj

@@ -81,7 +81,12 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.9.0" />
+    <PackageReference Include="Codecov" Version="1.5.0" />
+    <PackageReference Include="coverlet.msbuild" Version="2.6.3">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.2.0" />
     <PackageReference Include="System.Drawing.Common" Version="4.5.0-preview2-26406-04" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.extensibility.execution" Version="2.4.1" />