Progress: Begin fixing combining logic.

Progress: Begin fixing combining logic.

Have to add is_combining functions to detect combining for the purpose of FSS processing.

Skip past initial place holders in the skip functions.

The initial combining returns `F_complete_not_utf_start` only for combining at the start.
This should be then handled as a combining.

Begin adding the unit tests.
These should fail because the functionality that they are testing is not implemented.

What needs to be done next is to have all FSS processing code look past the special characters (except new lines).
Check for combining characters.