created a new folder with Makefile.am for the info files of the project
created a first skeleton of the texi file for documentation
Rename maxline constant to ARDUSERIAL_MAXLINE

libarduserial/arduserial.h,
libarduserial/arduserial.c:
* renamed the maxline constant to prevent naming conflicts
Autodetect checks if usb connections are available

libarduserial/arduserial.c:
* We check if there is a serial connection via usb possible and return
  -2 if thats not the case.

libarduserial/arduserial.h:
* Change MAXLINE constante to ARDUSERIAL_MAXLINE to prevent naming
  conflicts