Mark TODO compilation of arduserialtools.c done.
Implement ser_listarduinos(void) prodecure.

Remove the arduserialtools.c file and merge its former content into the
arduserial.c file.  It made to sense to work on two shared libraries.

Create new functionality for the end user.  We can list all the arduino
controllers connected to the computer with the new
ser_listarduinos(void) procedure. Also implemented some basic tests for
that procedure.
Add TODO task to README.