On Linux kernels the size of the values exported for network
device bytes and packets has used a 64 bit integer for quite
some time (2.6+ IIRC). Make the procfs value extraction use
correct types and change internal types used to rate convert
these counters (within the NetworkIO Meter) 64 bit integers,
where appropriate.
RichString_writeFrom takes a top spot during performance analysis due to the
calls to mbstowcs() and iswprint().
Most of the time we know in advance that we are only going to print regular
ASCII characters.
If the current data is smaller than the previous one, either by a retrieve error
or a device removal or a original data wraparound, sanitize the value to zero.
Fixes: #299