gtkwave update

My previous version of getting gtkwave working was fine, but the window didn't always refresh correctly.

sudo port install gtk2 +quartz 
sudo port install gtk-quartz-engine +quartz
sudo port install gtkwave +quartz  

When you need the last 1MiB of a file.

MacOS/BSD doens't have the "head -c -1M" construct to get the last 1MiB of my file

filesize=$(stat -f %z main.log) && dd if=main.log bs=1 \ 
skip=$((filesize - 1048576)) > ~/chunk.log