[PATCH 00/08] Add lvm lv properties for lvm2app.

This patchset adds remaining lv properties for lvm2app, and adds
the lvm2app interfaces and interactive tests to exercise
the interface.

Changes since last patchset:
1. Added readahead attributes (lv_read_ahead, lv_kernel_read_ahead)
2. Incorporated most all Petr and Kabi's feedback comments, including
renaming of the fields, etc.  I did not change the 'get' function
prototype to return the property value rather than passing it in.
I will do this as a second patchset.
3. Updated comments describing new APIs in lvm2app.h

The only two lv properties not included now are still the float/percent
based properties, snap_percent and copy_percent.  These should be
refactored carefully and I did not want to delay these patches further.

All vg and pv properties and most lv properties may now be queried
with this patchset.