needed when installing a new Redis version. Thanks to Scott Kevill.
Fixes issue #335.

added lua struct c extension

Now Lua scripts dispatch Redis commands properly calling the call() function. In order to make this possible call() was improved with a new flags argument that controls how the Redis command is executed.

Set a 3.5 GB maxmemory limit with noeviction policy if a 32 bit instance without user-provided memory limits is detected.

Added tests checking ability of the scripting engine to reorder the output of commands with a random output regarding signle elements position in the multi bulk reply.

A few SORT tests made more resistant to false negatives resulitng from poor randomization of Redis hash function with one byte inputs.

Make SORT BY <constant> STORE ... to always produce the same output by force sorting, so that we have deterministic replication of this command.

SORT is now more deterministic: does not accept to compare by score items that have scores not representing a valid double. Also items with the same score are compared lexycographically. At the same time the scripting side introduced the ability to sort the output of SORT when sort uses the BY <constant> optimization, resulting in no specific ordering. Since in this case the user may use GET, and the result of GET can be null, converted into false as Lua data type, this commit also introduces the ability to sort Lua tables containining false, only if the first (faster) attempt at using just table.sort with a single argument fails.

Order output of commands returning random arrays using table.sort when called from Lua, partially fixing issue #165. The issue is yet not completely fixed since we can't add the REDIS_CMD_SORT_FOR_SCRIPT flag in SORT currently, both because it may contain NULLs and because it is not cool to re-sort everything at every call when instead this should be sorted only if BY <constant> is used.

minimal change to obuf-limits.tcl test to make sure there are no false positives with 32bit instances as well.

Lua reports line numbers off by one in error messages

setKey(): call the higher level wrapper setModifiedKey() instead of touchWatchedKey() even if currently they are exactly the same.

SORT with STORE removes key if result is empty. This fixes issue #227.