wddx serialize segmentation faults fixs.

Hi Folks, I managed to fix the segmantation fuatls in the wddx module when serialising data. I am not sure of the desrialise operation at this point. There is still possibly a problem with capacity but I am still investigating it. My approach was to spot where there seemd to memory allocation problems. In doing so I removed many uses of erealloc as a potential problem, these may not be a problem, but the removal makes the code more understandable. The other changes involved not relying on the len variable to hold the current len of the buffer to be allocated. Instead the new allocation size is determoined where possible form the current string length + the length of the additional string + 1 for the string terminator. I found many cases where the allowance for the terminator was left out or accounted for by being "generous". the attached dif file should be usefull. Cheers, Gerrit Thomson.