[patch] dCalloc

[p***@public.gmane.org]

dNew macro hides multiplication and can lead to integer overflows.

Patch implements dCalloc and replaces dNew with dCalloc wrapper so no
integer overflows are possible:

http://www.inventati.org/noname/dillo/dlib/dcalloc.patch

dwrite.patch is moved to http://www.inventati.org/noname/dillo/dlib/