Small update for the dutch translation

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Merge pull request #422 from Ansa89/italian-translation

Italian translation: update
Update German translation
Merge pull request #424 from sfan5/master

Update German translation
Merge pull request #420 from Impyy/dutch-update

Small update for the dutch translation
Fix missing header definitions for typing notifications
Merge pull request #425 from albel727/fix-missing-defs

Fix missing header definitions for typing notifications
Add SPTR() for referring to localized STRINGs as a whole
Stop relying on arithmetics for addfriend_status
Stop relying on arithmetics for file status notification
Stop relying on arithmetics for call status notification
Remove comments about arithmetic referencing
Bootstrap to more nodes at once. Randomize node selection a bit.
Merge branch 'no-arithmetics-for-i18n' of https://github.com/albel727/uTox

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unsigned overflowing is defined behaviour.
Reuse S and SLEN macros in drawstr macro

A minor step toward decoupling from particular i18n implementation.
Split i18n into separate files per language

This separates different languages into self-contained files,
with strict order-independent ID->STRING correspondence,
automatic fallback to English for untranslated IDs, and
a syntax closely resembling (but not really valid)
gettext's PO files, in case we ever migrate to it.

Also, two new IDs are added for future use:
LANG_NATIVE_NAME for the language name in the language itself,
and LANG_ENGLISH_NAME for the language name in English.
These are expected to be used e.g. in language choice menu.
Eventually.
Stop relying on hardcoded size for i18n tables
uTox default DNS requests now use tox3.
Check for recommended length limit when not using @ for DNS names.