go fmt
update file size & logging options

These settings work much better and optimize away a few hours
of runtime waiting around for scratch files to be made.
rename files s/_512.fio$/.fio/

Switched to variable block sizes a while ago. The block size is tracked
in the device metadata as well so it's easy enough to report.
print elapsed time & lines found
use custom colors to get better contrast

comment header in custom_colors.go explains where I got them
Use a small + glyph instead of circles in scatterplot
only load CSV data on demand

Instead of loading all data at once, load one csv at a time. This
should only use enough memory to load + data per file on each group
which is a much smaller subset of data than all data.

Because the files are processed in conf order, generally VFS cache
will work out nicely between redundant loads, so don't worry about
it for now and KISS