lib/core: remove ropes intrude import in stream
lib/core: remove ropes intrude import in stream

The intrude import of ropes in lib/core/stream was only due to the
ropification of the read_all_bytes.

As the leaves were too small to have a positive impact with the actual
threshold value being chosen here, we remove the ropification in the
read_all function.

This simplifies code a lot, and keeps out the intrude import of the
ropes module.

We also take advantage of this modification to start using codecs here
to decode the string.

Signed-off-by: Lucas Bajolet <7ee927989f658093d1603ebdd77063d48a82a2fc@gmail.com>

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