premature version number update in base

[Richard Frith-Macdonald]

For the new release of base there is a small binary incompatibility on 64bit 
systems (NSNotFound has changed, and now matches Apple behavior), so we need a 
new library version.
The new release will be 1.24.0 with a library version of 1.24

Yesterday I updated svn trunk preparatory for release, and shouldn't have done 
so until the actual point of release (I've reverted that change) ... so if you 
updated base yesterday you'll need to rebuild/relink everything else to work 
with the new library version (or update base from trunk again, to get back to 
the 1.23 library version).

Sorry for any inconvenience/confusion caused.