Fix building for external tools

ExternalToolProjects/DBMan/CustomMainForm.cs

@@ -10,7 +10,7 @@ using Community.CsharpSqlite.SQLiteClient;
 
 namespace BizHawk.DBManTool
 {
-	[ExternalTool("DBMan", "DB Manager")]
+	[ExternalTool("DBMan", Description = "DB Manager")]
 	public class CustomMainForm : Form, IExternalToolForm
 	{
 		public CustomMainForm()

ExternalToolProjects/ExtToolCommon.props

@@ -1,6 +1,6 @@
 <Project>
-	<Import Project="$(ProjectDir)../../Common.props" />
-	<Import Project="$(ProjectDir)../../CommonNullable.props" />
+	<Import Project="../Common.props" />
+	<Import Project="../CommonNullable.props" />
 	<PropertyGroup>
 		<CodeAnalysisRuleSet>$(ProjectDir)../../Common.ruleset</CodeAnalysisRuleSet>
 		<OutputPath>$(ProjectDir)bin/$(Configuration)/</OutputPath>

ExternalToolProjects/HelloWorld/CustomMainForm.cs

@@ -11,7 +11,7 @@ using DisplayType = BizHawk.Client.Common.DisplayType;
 namespace HelloWorld
 {
 	/// <remarks>All of this is example code, but it's at least a little more substantiative than a simple "hello world".</remarks>
-	[ExternalTool("HelloWorld", "An example of how to interact with EmuHawk")]
+	[ExternalTool("HelloWorld", Description = "An example of how to interact with EmuHawk")]
 //	[ExternalToolApplicability.SingleRom(CoreSystem.NES, "EA343F4E445A9050D4B4FBAC2C77D0693B1D0922")] // example of limiting tool usage (this is SMB1)
 	[ExternalToolEmbeddedIcon("HelloWorld.icon_Hello.ico")]
 	public partial class CustomMainForm : Form, IExternalToolForm