#8 Certain attributes to make text untranslatable

[Gabix]

In Wordfast, it is possible to turn on/off the following options:
- Use Double Strikethrough as untranslatable attribute;
- Use Highlight Gray 25% as untranslatable attribute;
- Use Marching Red Ants as untranslatable attribute.

Something similar should be implemented in Anaphraseus too to skip certain parts of text.