REBASE set code style and untabify
change file size vars to size_t to get 64-bit file sizes on 64-bit systems

size_t is already used throughout for sizes, but perhaps it should be long
so that there are 64-bit file sizes on all platforms.

refs #3624 https://dev.guardianproject.info/issues/3624
REBASE rename vars in set_value() so they are understandable
refactor get_value() to write directly into the buffer given to it

Before, this code was allocating lots of memory, and making multiple copies
of things.  It would allocate chunks of memory the size of the entire file
no matter how small the read.  There is not need for such silliness since
a buffer and size is handed to sqlfs_proc_read() and sqlfs_proc_readlink(),
the two main users of get_value().  So this refactors things to just put
the data directly into that buffer as it is being read.
set_value() check the result of the previous block write before proceeding

This needs more work, check the //TODO