Remove unused references

Author: napen123

MathInterpreter/App.xaml.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Configuration;
-using System.Data;
 using System.Linq;
 using System.Threading.Tasks;
 using System.Windows;

MathInterpreter/MathInterpreter.csproj

@@ -55,18 +55,13 @@
       <Private>True</Private>
     </Reference>
     <Reference Include="System" />
-    <Reference Include="System.Data" />
     <Reference Include="System.Windows.Forms" />
     <Reference Include="System.Windows.Interactivity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
       <HintPath>..\packages\MahApps.Metro.1.2.4.0\lib\net40\System.Windows.Interactivity.dll</HintPath>
       <Private>True</Private>
     </Reference>
     <Reference Include="System.Xml" />
-    <Reference Include="Microsoft.CSharp" />
     <Reference Include="System.Core" />
-    <Reference Include="System.Xml.Linq" />
-    <Reference Include="System.Data.DataSetExtensions" />
-    <Reference Include="System.Net.Http" />
     <Reference Include="System.Xaml">
       <RequiredTargetFramework>4.0</RequiredTargetFramework>
     </Reference>