[CONUTILS] Split stream.c into input and output stream modules.

[CONUTILS] Split stream.c into input and output stream modules.

As code grows, this will allow for better maintenance of the console
stream code. In particular the input stream module will contain special
code for handling TTYs, and this is something not all console programs
will need. Having this code in a separate module will allow for the linker
to possibly remove this code when it is unused.