Compatibility with Unity3D

[DA-Assets]

Hello!

I am planning to use this library with Unity3D, but I noticed that it uses "dynamic" and ExpandoObject, which Unity does not support.

It seems that I managed to remove these dependencies from the library, and everything works fine, but since I am not familiar with the internals of MiniExcel, I can't be 100% sure that I didn't break anything.

However, it seems that making the library fully compatible with Unity3D is not too difficult.

Could you provide such support by default, avoiding the use of System.Dynamic in your library?

Thank you for the great library!