Some code and comment cleanup

- Remove all references to split points
- Some grammar and spelling fixes

No Functional change

Resolves #478

src/search.cpp

@@ -539,12 +539,7 @@ void Thread::search(bool isMainThread) {
 
 namespace {
 
-  // search<>() is the main search function for both PV and non-PV nodes and for
-  // normal and SplitPoint nodes. When called just after a split point the search
-  // is simpler because we have already probed the hash table, done a null move
-  // search, and searched the first move before splitting, so we don't have to
-  // repeat all this work again. We also don't need to store anything to the hash
-  // table here: This is taken care of after we return from the split point.
+  // search<>() is the main search function for both PV and non-PV nodes
 
   template <NodeType NT>
   Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) {