Implementing GUID using boost

I haven't taken a look at the hash table stuff, so I didn't touch that, but I was able to get rid of our (respectable!) guid random number seeding stuff in `guid_init`, etc. I ran the test suite and uncovered one problem which I was able to fix. I also started the program with a moderately sized chart and transactions (my mom's business's books), and everything seems good.
The C++11 way:
```
unsigned int destspot {0};
for (auto val_char : val)
    if (val_char != '-' && destspot < GUID_ENCODING_LENGTH)
       str[destspot++] = val_char;
```