count strings more accurately for stats

So far, only the few strings stored in stringitems were counted, but
many more strings are directly inserted into the cache. We account for
this now by identifying all these different strings and measure their
length. We are still not at the correct size of the cache in 'stats'
this way, but we are now again a bit closer.

Git-Dch: Ignore

0 files changed, 0 insertions, 0 deletions