Change access of member ImageEmbedder on Email object from internal t…

[MelzerJ]

In our project we need to extend the existing functionality of the EmailParser with different handling of the Postal Header and additionally integrate functionality to move css styles inline. Therefore we decided to write our own EmailParser implementing IEmailParser Interface. Unfortunately with the internal on the Email object we can't use the ImageEmbedder in our Parser. To ensure extensibility of the EmailParser the ImageEmbedder should be made accessable.

[mirogrenda]

+1 from me for this change