Update AppVeyor settings.

AppVeyor now runs builds on both Windows and Linux, using the latest
.Net Core SDK (3.0.100 at this time). Code coverage is only measured and
published on the Windows platform, and the NuGet package is also only
published from Windows.

appveyor.yml

@@ -1,64 +1,66 @@
 version: 1.0.{build}
-image: Visual Studio 2017
-init:
-- cmd: ''
+
+image:
+  - Ubuntu
+  - Visual Studio 2019
+
 environment:
+  CONFIGURATION: Release
   nugetKey:
     secure: jlkQ4lJxiapfC87YZMljFZbeROpo26F7wbEB7q+xn5xWlAyfOvy/SNrji8a5uKap
   codecovToken:
     secure: tDNSMb2HRVQsJEgwVvuqY02+qgaKI3bw0LHSqplQKSPSRJNEkdCVnX352HoSht5t
   COVERALLS_REPO_TOKEN:
     secure: ntYxuZR1S4QagcvXJ+rXGhJoIw0Ln556M3h6PQEwaGr/41x+JazkKeRJ8DHzHODc
-build_script:
-- cmd: >-
-    dotnet tool install coveralls.net  --version 1.0.0 --tool-path tools
-
 
 
+# Instll coverall.net only on Windows
+install:
+  - cmd: dotnet tool install coveralls.net --global --version 1.0.0
 
-    echo "tools\csmacnz.coveralls.exe --opencover -i ParserTests\coverage.opencover.xml --repoToken 4I3WBzHay1o8YwAH4xRskEHbi5w71atBP --commitBranch "%APPVEYOR_REPO_BRANCH%" --commitId "%APPVEYOR_REPO_COMMIT%" --commitAuthor "%APPVEYOR_REPO_COMMIT_AUTHOR%"  --commitEmail "%APPVEYOR_REPO_COMMIT_AUTHOR_EMAIL%" --jobId "%APPVEYOR_JOB_ID%" --useRelativePaths --basePath "%APPVEYOR_BUILD_FOLDER%"
-
-
-    dotnet restore
 
+build_script:
+  - ps: dotnet build -c $env:CONFIGURATION
 
-    dotnet build -c Release
 
+after_build:
+  - ps: dotnet pack -c $env:CONFIGURATION sly
 
 
+# Run coverage on Windows
+test_script:
+  - sh: dotnet test -c $CONFIGURATION --no-build
+  - cmd: dotnet test -c %CONFIGURATION% --no-build /p:CollectCoverage=true /p:CoverletOutputFormat=opencover /p:exclude=\"[while]*,[expressionParser]*,[GenericLexerWithCallbacks]*,[jsonparser]*,[SimpleExpressionParser]*\" ParserTests/ParserTests.csproj
 
-     dotnet test /p:CollectCoverage=true /p:CoverletOutputFormat=opencover /p:exclude=\"[while]*,[expressionParser]*,[GenericLexerWithCallbacks]*,[jsonparser]*,[SimpleExpressionParser]*\" ParserTests/ParserTests.csproj
 
-    echo "############################"
+# Publish coverage to Coverall on Windows
+after_test:
+  - ps: |
+      if ($isWindows) {
+        csmacnz.Coveralls --opencover -i ./ParserTests/coverage.opencover.xml --repoToken 4I3WBzHay1o8YwAH4xRskEHbi5w71atBP --commitBranch "%APPVEYOR_REPO_BRANCH%" --commitId "%APPVEYOR_REPO_COMMIT%" --commitAuthor "%APPVEYOR_REPO_COMMIT_AUTHOR%"  --commitEmail "%APPVEYOR_REPO_COMMIT_AUTHOR_EMAIL%" --jobId "%APPVEYOR_JOB_ID%"
+      }
 
 
-    tools\csmacnz.coveralls.exe --opencover -i ./ParserTests/coverage.opencover.xml --repoToken 4I3WBzHay1o8YwAH4xRskEHbi5w71atBP --commitBranch "%APPVEYOR_REPO_BRANCH%" --commitId "%APPVEYOR_REPO_COMMIT%" --commitAuthor "%APPVEYOR_REPO_COMMIT_AUTHOR%"  --commitEmail "%APPVEYOR_REPO_COMMIT_AUTHOR_EMAIL%" --jobId "%APPVEYOR_JOB_ID%"
+artifacts:
+  - path: sly/bin/$(CONFIGURATION)/*.nupkg
+    name: sly
 
 
-    echo "############################"
+# Deploy nuget package from Windows
+deploy:
+  - provider: NuGet
+    skip_symbols: true
+    api_key:
+      secure: jlkQ4lJxiapfC87YZMljFZbeROpo26F7wbEB7q+xn5xWlAyfOvy/SNrji8a5uKap
+    on:
+      branch: dev
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
 
 
-    dotnet pack -c Release
-test_script:
-- ps: dotnet test ParserTests/ParserTests.csproj
-artifacts:
-- path: sly/bin/release/*
-  name: sly
-- path: sly_coverage.xml
-  name: sly
-- path: ParserTests/coverage.opencover.xml
-  name: sly
-deploy:
-- provider: NuGet
-  api_key:
-    secure: jlkQ4lJxiapfC87YZMljFZbeROpo26F7wbEB7q+xn5xWlAyfOvy/SNrji8a5uKap
-  skip_symbols: true
-  on:
-    branch: dev
 notifications:
-- provider: Email
-  to:
-  - [email protected]
-  on_build_success: true
-  on_build_failure: true
-  on_build_status_changed: true
+  - provider: Email
+    to:
+      - [email protected]
+    on_build_success: true
+    on_build_failure: true
+    on_build_status_changed: true