Fix: Replace Susz with Leszno

Susz is masculine, not neuter, so it should result in "Susz Mazowiecki",
"Susz Morski", and not "Susz Mazowieckie" or "Susz Morskie". However,
because order of the names whould not be changed, it was replaced with
Leszno, which is neuter.

Codechange: use \u to indicate unicode chars in strings (#8379)

With \x, we sometimes had to do the "" trick, as the length is not
predefined. With C++11 bringing \u to the specs, which has a preset
length, we no longer need the "" trick.

We set the strings to u8, to ensure all compilers use UTF-8 encoding
for the \u characters.

This was triggered by newer CLangs, which start to warn if you
use "" in the middle of a string, wondering if that was your
intention. It is a good question. And this is our answer :)

Fix: spelling for a few real town names (#7338)

Added special characters to mostly Slovak towns, a few Spanish, and one Turkish.

Fix: unicode characters in Romanian town names (#7141)

Many of these town names were using the 'a with ~ above it' character,
which should actually by 'a with u above it'. There were other missing
accents as well which I've added.

Fix: Remove duplicate French and Slovak town names

I've replaced some of the duplicate real town names with new real town
names in the French and Slovak sets.

Also, some Slovak town names were missing accents, so I've fixed those.

Fix: Remove duplicate town name "Huacho" (#7038)

Huacho appears twice in the Spanish town names list. This change removes
the second one, and replaces it with a new one: Medellin.