[Users] LCR db_only mode problem

[Juha Heinanen]

currently lcr module always loads gw and lcr tables into memory.
there used to be no db_mode variable in the early days of the module.
gws were always loaded into memory and lcr entries were never loaded.

then caching mode was added along with loading of lcr entries into
memory.  at that time db_mode variable was also introduced, but it only
affects load_gws function.  i guess db_mode was added just in case a bug
is found in caching version of load_gws and people need to go back to
old behavior.

caching mode was added, because it turned out that load_gws database
query was far too slow if there is a large number of gws/lcr entries.
so even if you would manage to make lcr module to work in db_only mode,
it would not do you any good.  also, there is no db only version of
from_gw/to_gw functions.

my conclusion of this messy situation is that i'll remove db_mode
altogether from lcr module.

-- juha