Move utility functions out of pe.c and other minor changes
Use statically allocated buffer with X509_NAME_online.

X509_NAME_oneline is probably using "malloc" to allocate the buffer, releasing the buffer with "yr_free" is not a good idea for two reasons:

- It breaks tools used for detecting memory leaks as the buffer is not allocated with "yr_malloc" but is freed with "yr_free"
- In Windows "yr_malloc/yr_free" use a different heap that the one used by standard "malloc/free", so you can not free with "yr_free" something allocated with "malloc"
Simplify the serial number length computation
Fix wrong identifier
Remove unnecessary counter decrement

number_of_signatures shouldn't be the index for the last signature, but the actual number of signatures.
Remove unnecessary call to BIO_set_close, BIO_CLOSE flag is set by default
Fix some possible memory leaks
Add Metaflows to "who's using YARA"