[PATCH] src: fix spelling typos in argp help text and error diagnostics

[Mark Wielaard]

On Sat, Dec 12, 2020 at 04:27:37AM +0300, Dmitry V. Levin wrote:
> Since all these help text strings are marked for translation, apply the fixes
> to translation strings as well, this helps to avoid translations becoming fuzzy.
> 
> lenght -> length
> occured -> occurred
> endianess -> endianness
> reversable -> reversible

Thanks. Pushed.