Fix HW Issue at startup

Fixed an issue where the GPUs would be initialized on first pool alive,
but the mining threads would end up being initialized on another pool
because it was selected right away.
Remove obsolete benchmark mode
This mode/setting is unusable left-over from SHA-256 cgminer. It does not work with Scrypt or other algorithms that are used in sgminer. Removed in single commit so it can be used as reference, if benchmark mode is added in the future.
remove old commented-out code
add lock when accessing mining_threads
Refactor and stability improvements when restarting threads
enable_device should not modify mining_threads because this is unsafe after initialization. it is also not necessary in most cases where it is currently used, except in initialization
refactored some of the new restart_mining_threads code and incorporated above change for better stability
properly handle disabled devices in restart_mining_threads when opt_removedisabled is set
total_devices was set incorrectly if the disabled devices were not at the end of devices, so total_devices is now always the number of detected devices, since that is what is in the devices variable
GPUs cannot be hotplugged
Changing disabled devices on pool switch is not possible if remove-disabled is set (enabled)
Fix bad lock
spaces/indent
unused preprocessor directive
more locks for devices
safer
fix broken disabled devices when remove-disabled is set
Remote config files

Config parser can now read config files stored remotely via
https/http/ftp. Requires libcurl.
Add BitBlock kernel
Add bitblock to source list
Shabal algo
Shabal header
Whirlpool header
Whirlpool algo