Python Serial Port Extension

As it noted in the documentation, with sufficiently new python versions the Serial class will inherit from RawIOBase. The readline implementation of RawIOBase does not allow the eol keyword argument to be passed, instead deriving its line ending from the newline keyword argument passed to the constructor. Unfortunately, the Serial constructor does not have a newline keyword argument. This is a severe regression.

While the RawIOBase approach is acceptable for some cases, it is convenient to be able to choose delimiters on a case-by-case basis when working with many serial devices. For this reason, it would be nice if a readuntil function were implemented in the Serial class, allowing one to easily read until some delimiting sequence (e.g. the old behavior of readline).