Update: Fix IKI write and add EKI write functions for f_iki.

Update: Fix IKI write and add EKI write functions for f_iki.

Fix the backslash handling now that I have figured that whole situation out and updated the specifications.

Adding support for the EKI write.

Add more extensive unit tests for both IKI write and EKI write.

I am trying to keep both the IKI write and the IKI write works functions as similar as possible.
The "works" write tests are already big enough anyway.
Implement a separate test for EKI, called `test__f_iki_eki_write__works_for_multiple`, to handle the multiple vocabularies case.
This will be structurally identical to the regular works tests but instead has multiple vocabularies.