changed projects to can compile with vs2015 (14.0)

src/Main/ICSharpCode.SharpDevelop.BuildWorker120/ICSharpCode.SharpDevelop.BuildWorker120.csproj

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="12.0">
+<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="14.0">
   <PropertyGroup>
     <ProjectGuid>{6F273DA5-E10C-45A6-9071-7313ECD98C90}</ProjectGuid>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
@@ -49,8 +49,8 @@
   </PropertyGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.Targets" />
   <ItemGroup>
-    <Reference Include="Microsoft.Build, Version=12.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
-    <Reference Include="Microsoft.Build.Framework, Version=12.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
+    <Reference Include="Microsoft.Build" />
+    <Reference Include="Microsoft.Build.Framework" />
     <Reference Include="System" />
     <Reference Include="System.Core">
       <RequiredTargetFramework>3.5</RequiredTargetFramework>

src/Main/ICSharpCode.SharpDevelop.BuildWorker140/ICSharpCode.SharpDevelop.BuildWorker140.csproj

@@ -1,5 +1,5 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="12.0">
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="14.0">
   <PropertyGroup>
     <ProjectGuid>{7BA66A6B-1ED8-4B4C-970C-8928E891418B}</ProjectGuid>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>