Merge remote-tracking branch 'origin/1.6' into 1.7

doc/sphinx/book/app/a-errcodes.rst

doc/sphinx/book/app/b-internals.rst

doc/sphinx/book/app/c-lua_tutorial.rst

doc/sphinx/book/app/d-plugins.rst

doc/sphinx/book/app/e-sophia/i1.png

doc/sphinx/book/app/e-sophia/i10.png

doc/sphinx/book/app/e-sophia/i12.png

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doc/sphinx/book/app/e-sophia/i14.png

doc/sphinx/book/app/e-sophia/i2.png

doc/sphinx/book/app/e-sophia/i3.png

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doc/sphinx/book/app/e-sophia/i5.png

doc/sphinx/book/app/e-sophia/i6.png

doc/sphinx/book/app/e-sophia/i7.png

doc/sphinx/book/app/e-sophia/i8.png

doc/sphinx/book/app/e-sophia/i9.png

doc/sphinx/book/app/e-sophia/index.rst

doc/sphinx/book/box/authentication.rst

doc/sphinx/book/box/box_index.rst