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
Merge branch 'no-arithmetics-for-i18n' of https://github.com/albel727/uTox

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unsigned overflowing is defined behaviour.