The y-axis graph labels in logarithmic mode display in 'scientific'
notation eg: '1e+00' for 0, '1e+01' for 10, '1e+02' for 100 and so on.
This IMO is a pain in the backside for non scientific humans to read.

Modified output to display numbers up to 99,999 in conventional decimal
format and to revert to scientific notation for larger, thus the same
display space is taken.

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>

While we're at it, relocate from libs/ to utils/ as it provides executables
and change the directory name from rrdtool-1.0.x to rrdtool1 to make it match
the source package name.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>