refactor: avoided using Lua 5.1's module() function for defining our Lua modules because it has bad side effects.
optimize: eliminated table.insert() because it is slower than "tb[#tb + 1] = val". thanks alex-yam for the patch in #22.
refactor: removed the empty string separator argument from the table.concat() call because it is already the default. thanks alex-yam for the patch in #22.
updated the copyright line in the source file. thanks alex-yam for the patch in #22.
feature: added new redis commands bitcount, bitop, client, dump, hincrbyfloat, incrbyfloat, migrate, pexpire, pexpireat, psetex, pubsub, pttl, restore, and time. thanks alex-yam for the patch in #22.
docs: do not use 0 (i.e., unlimited) max_idle_time in the set_keepalive() call in the code sample.