Display entire error message from avrdude upon failure

What change would like to see?
Display the complete error message from avrdude upon failure (see also 
Issue#301). For example, in the case of the following error:

avrdude: Device signature = 0x1e9406
avrdude: Expected signature for ATMEGA644P is 1E 96 0A
         Double check chip, or use -F to override this check.

avrdude done.  Thank you.

only the "Expected" value is shown, but not the signature actually read.

Why?

In the above case, knowing the signature actually read could help in diagnosing 
the cause of failure, e.g. shorted/grounded MISO pin (signature always read
000000 or FFFFFF), wrong chip ("close", consistent but wrong
signature), or floating MISO pin (misconnected or maybe target chip
not receiving a clock -> signature random/different every time).

Would this cause any incompatibilities with previous versions?  If so, how
can these be mitigated?

None that I know of

Original issue reported on code.google.com by drmn...@gmail.com on 22 Jul 2010 at 10:15

laesaster / arduino

Display entire error message from avrdude upon failure #303