This helped locate some bugs:
* read() could read past EOF due to BFile_Read() allowing you to read up
until the end of the last sector, beyond the file size
* pread() did not restore the file offset because the negative seek at
the end is not relative (that was the CASIOWIN fs API), so pread()
could not actually be written without knowing the current position
* lseek() would clamp you to EOF but still return its out-of-bounds
arguments, as a direct result of BFile_Seek() doing that
Benefits:
* Made pread() a generic function
Lephe