Assorted trivial cleanups 3/2019 (#2030)

No functional change.

src/thread.cpp

@@ -31,7 +31,7 @@ ThreadPool Threads; // Global object
 
 
 /// Thread constructor launches the thread and waits until it goes to sleep
-/// in idle_loop(). Note that 'searching' and 'exit' should be alredy set.
+/// in idle_loop(). Note that 'searching' and 'exit' should be already set.
 
 Thread::Thread(size_t n) : idx(n), stdThread(&Thread::idle_loop, this) {