Support umlauts and other languages

[RokasVaitkevicius]

It seems that myna parser and its 'letters' range doesn't support other languages than english. I spotted that in german it removes umlauts.
For example:
würdest du lieber
after parsing becomes
wrdest du lieber.

I have tested other umlauts, same outcome. I guess other languages like french would have the same issue too.

To fix this I guess we can do two things, either fix it in myna parser which is not actively maintained, so I am afraid, that it would be hard to get support from that, or try adding these special letters with other special characters.

[rmtuckerphx]

Let's try adding these special letters with other special characters. Anybody else have a suggestion.
Thanks @RokasVaitkevicius

[digitalica]

for me this works ok now: in the editor I typed this example and other special chars and i can't reproduce it.

[arjan]

seems to work