Bugfix write newline

[tiagolobao]

Hello!

First of all thanks for making this port to arduino! I'm using in my project that is based on avr now.

I had a problem that when I was printing new line with addch, and when I was trying to delete the previous character with delch, I had problem trying to move back to a relative position like x = x - 1. And I found out the problem that the cursor y and x was not being updated properly. (I'm making a CLI/Shell in my project)

All the functions like getnstr and editLine they just avoid the KEY_CR so I think it was not being printed at all in previous projects. And I also tried my changes with some of the examples and they seem to work just fine.

So, if you want, you can add this change to the library. Any questions / further testing just ping me Thanks!