assignments for strings longer than 2 chars
- Use strlcpy concatenation instead of strlcat
- Make sure that what remains of iteration of the '_len' variable
for manual char assignment
is done in a safer way so mistakes are less possible
as deprecated.
* Use fill_pathname_join_special in the vast majority of cases where
we can ensure out_path is a new empty string
* Get rid of some extension concatenation with strlcat where encountered
* Some general cleanups with NULL termination of strings that get immediately
passed to strlcpy/strlcpy-adjacent functions
