Scripting: add helper functions redis.error_reply() and redis.status_reply().
Scripting: add helper functions redis.error_reply() and redis.status_reply().

A previous commit introduced Redis.NIL. This commit adds similar helper
functions to return tables with a single field set to the specified
string so that instead of using 'return {err="My Error"}' it is possible
to use a more idiomatic form:

    return redis.error_reply("My Error")
    return redis.status_reply("OK")

jaambee/redis,janeasystems/redis,hanmichael/redis,LittlePeng/redis,grisha/thredis,powerumc/MyRedis_old,kolonse/redis,daogangtang/redis_luajit2.6,sidsen/redis,miminus/redis,ScottKaiGu/redis,Jonavin/redis,oaastest/redis,daogangtang/redis_luajit2.6,damy/redis,enginekit/redis,hanmichael/redis,adamweixuan/redis,upsoft/redis,jaambee/redis,miminus/redis,nandhanurrevanth/redis,jacklee0810/redis,miminus/redis,fanxu/redis,liqiang199105/redis,Cybermaxs/redis,ideaar/redis,DeNA/redis,DeNA/redis,kolonse/redis,alpha8/redis,hanmichael/redis,richmonkey/netleveldb,jaambee/redis,alpha8/redis,shanegxxiao/redis,damy/redis,powerumc/MyRedis_old,fanxu/redis,Jonavin/redis,kolonse/redis,crask/redis-cutter,Cybermaxs/redis,Cybermaxs/redis,grisha/thredis,damy/redis,shanegxxiao/redis,quangnguyen90/redis,LittlePeng/redis,enginekit/redis,richmonkey/netleveldb,kts12345/redis,fanxu/redis,liqiang199105/redis,Jonavin/redis,jaambee/redis,upsoft/redis,oaastest/redis,LittlePeng/redis,jacklee0810/redis,nandhanurrevanth/redis,damy/redis,powerumc/MyRedis,kts12345/redis,liqiang199105/redis,jacklee0810/redis,grisha/thredis,laurencee/redis,erwin00776/redis-2.8-optimize,powerumc/MyRedis_old,miminus/redis,jqk6/redis,enginekit/redis,janeasystems/redis,enginekit/redis,quangnguyen90/redis,ideaar/redis,shanegxxiao/redis,crask/redis-cutter,upsoft/redis,erwin00776/redis-2.8-optimize,Jonavin/redis,ideaar/redis,jqk6/redis,quangnguyen90/redis,jqk6/redis,damy/redis,ScottKaiGu/redis,janeasystems/redis,daogangtang/redis_luajit2.6,sidsen/redis,laurencee/redis,Cybermaxs/redis,StartTheShift/redis-shift,jqk6/redis,daogangtang/redis_luajit2.6,upsoft/redis,powerumc/MyRedis_old,kts12345/redis,janeasystems/redis,erwin00776/redis-2.8-optimize,alpha8/redis,Cybermaxs/redis,ideaar/redis,StartTheShift/redis-shift,jaambee/redis,sidsen/redis,DeNA/redis,erwin00776/redis-2.8-optimize,nandhanurrevanth/redis,grisha/thredis,alpha8/redis,kts12345/redis,adamweixuan/redis,jacklee0810/redis,sidsen/redis,quangnguyen90/redis,Jonavin/redis,liqiang199105/redis,shanegxxiao/redis,ScottKaiGu/redis,ScottKaiGu/redis,crask/redis-cutter,laurencee/redis,powerumc/MyRedis,kolonse/redis,richmonkey/netleveldb,jacklee0810/redis,oaastest/redis,sidsen/redis,kolonse/redis,upsoft/redis,StartTheShift/redis-shift,adamweixuan/redis,adamweixuan/redis,adamweixuan/redis,laurencee/redis,jqk6/redis,shanegxxiao/redis,kts12345/redis,oaastest/redis,richmonkey/netleveldb,nandhanurrevanth/redis,liqiang199105/redis,fanxu/redis,hanmichael/redis,hanmichael/redis,enginekit/redis,miminus/redis,powerumc/MyRedis,nandhanurrevanth/redis,quangnguyen90/redis,ideaar/redis,janeasystems/redis,sidsen/redis,ScottKaiGu/redis,oaastest/redis,laurencee/redis,alpha8/redis