clean up code.
add a hash function for string.
do not care about time less than a second.
separate file handling functions.
do not include an unnecessary header file.
rename file names.
rename function, variable and constant names due to file name changes.
add a function to fill a packet buffer with zero.
separate a locator table from a main table for performance.
handle more than one response messages.
cosmetic change.
use size_t, not off_t, for a file size.
encode ``when'' as duration, not time.
fix the wrong definition of a query size.
fix the wrong place of double space to put when dumping a packet.
consider time that a client specifies when searching database.
fix the wrong duration encoding.
support new file format of database import file.
dump a time to be required to resolve locators.
open database files at boot time, not at each read or write.