Assorted tweaks from DON

Mainly renames and some little code style improvment,
inspired by looking at DON sources:

https://github.com/erashid/DON

No functional change.

src/main.cpp

@@ -40,7 +40,7 @@ int main(int argc, char* argv[]) {
   Pawns::init();
   Eval::init();
   Threads.init();
-  TT.set_size(Options["Hash"]);
+  TT.resize(Options["Hash"]);
 
   std::string args;