Peter M. Groen / redox

Uses libev timer watchers to queue commands on a regular
interval. Very fast. Still need to handle deactivation of
timers from the user side.

num_commands_processed(), trarcks using cmd_count and guarded
with queue_guard.

Used to block the main thread until the event loop is stopped by
calling the .stop() method. Implemented using a condition_variable,
and very useful for clients.

Improved examples, added a threaded getter/setter example
and cleaned up the other. Generally refactored code in the
core files and cleaned up the details to make the slickest
possible API. Implemented a to_exit variable as a stop
condition for the event thread.

The event loop (now libev) now runs in a separate detached thread,
which is abstracted away from the user, who only calls a nonblocking
.start() method. This thread loops continously, alternating telling
Redis about asynchronous commands ready to send, and running one
iteration of the event loop, where all pending events are taken
care of. This greatly simplifies the user code.

Additionally, some clever tricker is implemented now to handle
memory management well with the templated command types. The
difficulty comes from the fact that we pass redis a void pointer
only, and must retreive everything from that (so, we can't use
shared_ptr for the whole thing). Thus, we use maps of void pointers
to their templated data structure pointers, where the memory address
of the pointer serves as the key.

Basic CMake setup, redisx implementation, and one example program.