aqhome: make datafile a virtual class. Add datafile_direct.

this is to allow for cached data file handling later.

aqhome/data/0BUILD

@@ -30,6 +30,7 @@
     <setVar name="local/typefiles" >
       value.t2d
       device.t2d
+      datafile.t2d
     </setVar>
   
     <setVar name="local/built_sources" >
@@ -56,7 +57,7 @@
   
     <headers dist="true" install="$(pkgincludedir)/data" >
       storage.h
-      datafile.h
+      datafile_direct.h
     </headers>
 
 
@@ -64,7 +65,7 @@
       storage_p.h
       storage_readxml.h
       storage_writexml.h
-      datafile_p.h
+      datafile_direct_p.h
     </headers>
   
   
@@ -74,7 +75,7 @@
       storage.c
       storage_readxml.c
       storage_writexml.c
-      datafile.c
+      datafile_direct.c
     </sources>