_MAJOR_ refactoring and stripping

Separated C++ code more clearly, and firmly, into classes. Stripped out
practically all of the solo-specific code. Disabled CPU mining. Changed
config file format. Unlinked vault code. Tightened up some loose screws.
Added a dev fee. Enabled multi-GPU mining and other multi-threaded
operations. Decoupled UI output from mining loop almost entirely (it
still updates the rate counters).

Added LICENSE file and (version-specific) README.

README.txt

@@ -0,0 +1,27 @@
+  This version is a bit of a departure, hence "gaiden". Configuration
+is entirely file-based, in `0xbitcoin.json', which _is_ read by a
+proper JSON interpreter, so formatting is
+important. https://jsonlint.com/ is quite useful for checking, if you
+have any difficulty.
+
+	You will have to supply your own Ethereum address (mine is there as
+a placeholder - please don't actually mine to it!) and select a
+server.
+	CUDA devices are numbered starting at 0, which is the "most capable"
+card according to Nvidia's criteria - not always accurate, but
+generally at least close. Specific devices can be disabled if desired,
+and per-card intensity is, hopefully obviously, supported easily. Have
+no worries about specifying cards that don't exist: such settings are
+simply ignored.
+
+	Once your configuration is complete, simply double-click on the
+miner and enjoy. No more faffing about with arcane batch file syntax,
+piping commands and so on. Pool mining only, I'm afraid.
+
+	There is, finally, a ~2.5% dev fee. The implementation is simple and
+uses a foolproof (though I tested it anyway!) counter: it merely
+diverts every 41st share to my address. Dev shares are not indicated
+in your solution counter, but instead trigger a log message containing
+a counter so that you can verify the ratio and timing.
+
+  Happy mining!

binding.gyp

@@ -13,11 +13,12 @@
         "cpp/hybridminer/addon.cc",
         "cpp/hybridminer/hybridminer.cpp",
         "cpp/hybridminer/cpusolver.cpp",
+        "cpp/hybridminer/miner_state.cpp",
         "cpp/hybridminer/sha3.c",
         "cpp/hybridminer/cudasolver.cpp",
         "cpp/hybridminer/cuda_sha3.cu"
       ],
-      'cflags_cc+': [ '-march=native', '-O3', '-std=c++11' ],
+      'cflags_cc+': [ '-march=native', '-O3', '-std=c++11', '-Wall' ],
 
 # Comment next line for test builds
       'defines': [ 'NDEBUG'],
@@ -88,7 +89,8 @@
               'MultiProcessorCompilation': 'true',
               'Optimization': 3,
               'RuntimeLibrary': 0,
-              'WarningLevel': 3,
+              'WarningLevel': 4, # Wall is _completely batshit_ in MSVC
+              'DisableSpecificWarnings': ['4100'], # formal argument not used
               'ExceptionHandling': 1,
               'DebugInformationFormat': 3
             }