Add properties.[ch] to lib/report, defined based on columns.h.

Add properties.[ch] to lib/report, defined based on columns.h.

Extend the existing reporting infrastructure definitions and structures
to include a 'get' and 'set' function for each field.  We will provide
a 'get' and 'set' function for each of these fields, which will be utilized
by exported lvm2app functions.

Define a default _not_implemented 'get' and 'set' function that just sets
an errno and returns 0.  Future patches will actually implement the
specific 'get' and 'set' functions for each property.  For read-only
properties, only the 'get' function will be implemented.

Define vg_get_property() function to query a property.  We will call
this from a lvm2app function.