[BFG-dev] 3.1: new dependencies

[Luke-Jr]

Packagers, please note 3.1 will have 2 new dependencies:
- uthash-dev 1.9.2+ is mandatory
- libsensors is optional, for Radeon temperature sensors with free/Mesa OpenCL

Also note that you can now build against a system (independently packaged) 
libblkmaker using the --with-system-libblkmaker configure option.

Avalon support will now be enabled by default, and should not affect other 
mining use.

CPU mining should build support for SSE/assembly optimized routines as long as 
the compiler supports it, even if the chosen CFLAGS do not; they will be 
disabled at runtime if the processor doesn't work with them.

I'm hoping to do the release sometime within the next week, so please update 
and test the packaging scripts when you get a chance. Let me know if there are 
any troubles.

Thanks,

Luke