Upgrade to .NET 3.0 (microsoft#1521)

* Upgrade to 3.0

* Get back to 2.0

Author: Mikhail Arkhipov

src/Analysis/Ast/Test/FluentAssertions/AssertionsUtilities.cs

@@ -24,6 +24,7 @@
 using Microsoft.Python.Core;
 using Microsoft.Python.Core.Text;
 using Microsoft.Python.Parsing;
+using Range = Microsoft.Python.Core.Text.Range;
 
 namespace Microsoft.Python.Analysis.Tests.FluentAssertions {
     public static class AssertionsUtilities {

src/Analysis/Ast/Test/Microsoft.Python.Analysis.Tests.csproj

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
     <RootNamespace>Microsoft.Python.Analysis.Tests</RootNamespace>
     <AssemblyName>Microsoft.Python.Analysis.Tests</AssemblyName>
   </PropertyGroup>

src/Core/Test/Microsoft.Python.Core.Tests.csproj

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.2</TargetFramework>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
     <RootNamespace>Microsoft.Python.Core.Tests</RootNamespace>
     <AssemblyName>Microsoft.Python.Core.Tests</AssemblyName>
   </PropertyGroup>

src/LanguageServer/Impl/Formatting/BlockFormatter.cs

@@ -24,6 +24,7 @@
 using Microsoft.Python.Core.Diagnostics;
 using Microsoft.Python.Core.Text;
 using Microsoft.Python.LanguageServer.Protocol;
+using Range = Microsoft.Python.Core.Text.Range;
 
 namespace Microsoft.Python.LanguageServer.Formatting {
     /// <summary>

src/LanguageServer/Impl/Formatting/LineFormatter.cs

@@ -24,6 +24,7 @@
 using Microsoft.Python.Core.Text;
 using Microsoft.Python.LanguageServer.Protocol;
 using Microsoft.Python.Parsing;
+using Range = Microsoft.Python.Core.Text.Range;
 
 namespace Microsoft.Python.LanguageServer.Formatting {
     /// <summary>

src/LanguageServer/Impl/LanguageServer.cs

@@ -25,14 +25,14 @@
 using Microsoft.Python.Core.Idle;
 using Microsoft.Python.Core.Logging;
 using Microsoft.Python.Core.Services;
-using Microsoft.Python.Core.Text;
 using Microsoft.Python.Core.Threading;
 using Microsoft.Python.LanguageServer.Extensibility;
 using Microsoft.Python.LanguageServer.Protocol;
 using Microsoft.Python.LanguageServer.Telemetry;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 using StreamJsonRpc;
+using Range = Microsoft.Python.Core.Text.Range;
 
 namespace Microsoft.Python.LanguageServer.Implementation {
     /// <summary>

src/LanguageServer/Impl/Microsoft.Python.LanguageServer.csproj

@@ -1,6 +1,6 @@
 <Project>
     <PropertyGroup>
-        <TargetFramework>netcoreapp2.2</TargetFramework>
+        <TargetFramework>netcoreapp3.0</TargetFramework>
         <RootNamespace>Microsoft.Python.LanguageServer</RootNamespace>
         <AssemblyName>Microsoft.Python.LanguageServer</AssemblyName>
     </PropertyGroup>

src/LanguageServer/Impl/Protocol/Classes.cs

@@ -16,8 +16,8 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using Microsoft.Python.Core.Text;
 using Newtonsoft.Json;
+using Range = Microsoft.Python.Core.Text.Range;
 
 namespace Microsoft.Python.LanguageServer.Protocol {
     [Serializable]

src/LanguageServer/Impl/Protocol/Messages.cs

@@ -17,6 +17,7 @@
 using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 using Microsoft.Python.Core.Text;
+using Range = Microsoft.Python.Core.Text.Range;
 
 namespace Microsoft.Python.LanguageServer.Protocol {
     [Serializable]

src/LanguageServer/Impl/Sources/HoverSource.cs

@@ -13,7 +13,6 @@
 // See the Apache Version 2.0 License for specific language governing
 // permissions and limitations under the License.
 
-using System;
 using Microsoft.Python.Analysis;
 using Microsoft.Python.Analysis.Analyzer;
 using Microsoft.Python.Analysis.Analyzer.Expressions;
@@ -25,6 +24,7 @@
 using Microsoft.Python.LanguageServer.Completion;
 using Microsoft.Python.LanguageServer.Protocol;
 using Microsoft.Python.Parsing.Ast;
+using Range = Microsoft.Python.Core.Text.Range;
 
 namespace Microsoft.Python.LanguageServer.Sources {
     internal sealed class HoverSource {