Big cleanup of rampant using std.

watcher.cpp

@@ -1,13 +1,14 @@
 #include "watcher.hpp"
 #include <filesystem>
-using namespace std;
+
+using std::string;
 namespace fs = std::filesystem;
 
 void UpdateListener::handleFileAction(efsw::WatchID watchid,
-    const std::string& dir,
-    const std::string& filename,
+    const string& dir,
+    const string& filename,
     efsw::Action action,
-    std::string oldFilename)
+    string oldFilename)
 {
 
   // this is some gnarly BS here, probably tons