made dropFileExtension() a function usable from anywhere

changed dropFileExtension() implementation

BaseLib/FileTools.cpp

@@ -87,7 +87,7 @@ std::string dropFileExtension(std::string const& filename)
 	if (p == std::string::npos)
 		return filename;
 
-	return filename.substr(0, filename.length() - p);
+	return filename.substr(0, p);
 }
 
 std::string extractBaseName(std::string const& pathname)

BaseLib/FileTools.h

@@ -75,6 +75,11 @@ std::string getFileExtension(std::string const& filename);
  */
 bool hasFileExtension(std::string const& extension, std::string const& filename);
 
+/** Returns a string with file extension as found by getFileExtension()
+ * dropped.
+ */
+std::string dropFileExtension(std::string const& filename);
+
 /**
  * Checks if file_name already contains a qualified path and if not copies the
  * path from source.