[net] fix and exception with HttpOpenRequest()

* As the MSDN doc says, "Failing to properly terminate the (lplpszAcceptTypes)
  array with a NULL pointer will cause a crash."
* Also switch to HttpSendRequestA() since we have no use for W there.
[core] add UDF filesystem support

* Only supported on Vista or later
* Also disable exFAT for XP (requires a KB => not worth it)
* Also improve display of partition data for type 0x07
* Also fix and issue where exFAT/UDF would try to modify PBR
* Also logically move and simplify some of the code
* Closes #157