Update README

Changes to differentiate filenames in 32-bit vs. 64-bit SDK installation
Implement cg_lock write biased rwlocks.
Merge pull request #402 from hocuscapocus/patch-1

Update README
Merge branch 'master' of github.com:ckolivas/cgminer
Remove unused qd_lock.
Convert the control_lock to a cg_lock.
Convert the ch_lock to cg_lock.
Move the stratum and GBT data to be protected under a new cg_lock data_lock.
Add intermediate variants of cglocks that can be up or downgraded to read or write locks and use them for stratum work generation.
Convert gbt_lock to a cg_lock.
Merge pull request #403 from kanoi/bflsc

USB add --usb options to limit USB device selection v0.1 + --usb-dump display brief dump if value = 0
Sacrifice the ram of curl handles in stratum disconnects when we have built with old libcurl to avoid crashes.
Merge branch 'master' of github.com:ckolivas/cgminer
Only curl easy cleanup a stratum curl if it exists.
Make pool adding while running asynchronous, using the pool test thread functionality.
Merge pull request #404 from kanoi/bflsc

cgminer -n to include a USB device list