Handle file rescan (#2951)

* Fire handlers when file updated or moved
* Create galleries as needed
* Clean empty galleries
* Handle cleaning zip folders when path changed
* Fix gallery association on duplicate images
* Re-create missing folder-based galleries

pkg/fsutil/dir.go

@@ -34,6 +34,17 @@ func IsPathInDir(dir, pathToCheck string) bool {
 	return false
 }
 
+// IsPathInDirs returns true if pathToCheck is within anys of the paths in dirs.
+func IsPathInDirs(dirs []string, pathToCheck string) bool {
+	for _, dir := range dirs {
+		if IsPathInDir(dir, pathToCheck) {
+			return true
+		}
+	}
+
+	return false
+}
+
 // GetHomeDirectory returns the path of the user's home directory.  ~ on Unix and C:\Users\UserName on Windows
 func GetHomeDirectory() string {
 	currentUser, err := user.Current()