vchoi_fork

Checkin of fixes for a number of bugs in reads to page 0, and in file
open in the VFD SWMR reader case.

Note that the following failures in testvfdswmr.sh:

1) Unable to find metadata file on VFD SWMR reader open.

2) Occasional sanity check failures in the page buffer on raw data write.

3) Filter failures on raw data read in VFD SWMR readers when compression
   is enabled.

4) Unexpected data errors in VFD SWMR readers when compression is
   disabled.

Note that I expect that items 3 & 4 two aspects of the same issues -- the
fact that we don't guarantee that raw data is consistent with metadata.

Item 2) must be addressed, but it is so infrequent that it isn't doesn't
affect the conclusion VFD SWMR seems to work, and thus it can wait until
phase 2.

I am given to understand that Vailin has largely addressed item 1),
and will be checking in her solution to this soon.

Tested on Charis and Jelly.