Address 2020 compatibility issues, relocate export menu item, and other items

[brawner]

This addresses compatibility issues with SW 2020 as well as some minor improvements. It relocates the "Export as URDF" button to the "Tools" menu.

[jaytjoa]

Hi, the issue in the SOLIDWORKS 2020 is solved by using the exe in #105. Thank you for good support!

[mis-eu]

Build error after applying this patch https://github.com//issues/105#issuecomment-704651739

Severity	Code	Description	Project	File	Line	Suppression State
Warning		Type library exporter warning processing 'SW2URDF.UI.IMessageBox.Show(#0), SW2URDF'. Warning: Non COM visible value type 'System.Windows.MessageBoxResult' is being referenced either from the type currently being exported or from one of its base types.	SW2URDF			
Warning		Type library exporter warning processing 'SW2URDF.UI.IMessageBox.Show(#0), SW2URDF'. Warning: Non COM visible value type 'System.Windows.MessageBoxResult' is being referenced either from the type currently being exported or from one of its base types.	SW2URDF			
Warning	CA1063	Provide an overridable implementation of Dispose(bool) on 'SWTestFixture' or mark the type as sealed. A call to Dispose(false) should only clean up native resources. A call to Dispose(true) should clean up both managed and native resources.	SW2URDF			Active
Warning		Registering an unsigned assembly with /codebase can cause your assembly to interfere with other applications that may be installed on the same computer. The /codebase switch is intended to be used only with signed assemblies. Please give your assembly a strong name and re-register it.	SW2URDF	C:\Users\Fiona\Desktop\solidworks_urdf_exporter\SW2URDF\RegAsm		
Warning	CA1816	Change 'SWTestFixture.Dispose()' to call 'GC.SuppressFinalize(object)'. This will prevent derived types that introduce a finalizer from needing to re-implement 'IDisposable' to call it.	SW2URDF	C:\Users\Fiona\Desktop\solidworks_urdf_exporter\SW2URDF\Test\SWTestFixture.cs	26	Active
Warning	CA1063	Modify 'SWTestFixture.Dispose()' so that it calls Dispose(true), then calls GC.SuppressFinalize on the current object instance ('this' or 'Me' in Visual Basic), and then returns.	SW2URDF	C:\Users\Fiona\Desktop\solidworks_urdf_exporter\SW2URDF\Test\SWTestFixture.cs	26	Active  

[brawner]

@mis-eu I don't see an error, I just see warnings. Those warnings were present on my system so it looks like it succeeded for you!