Backported fix for Heap Overflow in Floating Point Parsing (CVE-2013-4164)

This fix was backported by Tobias Kraze of makandra:
http://makandracards.com/railslts/19977-backported-fix-for-heap-overflow-in-floating-point-parsing-cve-2013-4164
Bump patchlevel to p375. Add note to README/ChangeLog