* libarduserial/arduserial.c (ser_readln): fixed a bug where the program
did not expect a cariage return, expexted new line. improved performance
slightly.
* testsuite/arduserial/testreadln.c (main): translated a debug message
into english. Added a check for the length of the read string. Check
for nul termination of the read string. added a constant to store the
the message the arduino sends.