Regression Serial monitor OOM back in 1.0.6, 1.5.7+

[xxxajk]

When displaying lots of data at high speed the JVM will run out of memory (OOM).
This issue is more noticeable on 32bit where the buffer is obviously going to be smaller.
This was fixed in 1.0.5 by truncating the buffer to a manageable size.

[cmaglie]

Closing ad duplicate of #2233