fixed extension for iges files

.igs seems to be a bit more common than .iges
fix incorrect handling of parts with no parameters
nicer output of standards in task page
regenerated html
fixed description of missing common parameters
fixed part number statistics

did not count identical standards. This is also a valid way to count,
but I prefer it to be consistent with the number of files in the IGES
distribution.
added some small ball bearing types

and some cosmetic
added imperial ball bearings
fillet radius for single row radial bearings
added note to needle roller