Configurable Column Widths (#360)

* add configurable column widths

* reorder to match config file

* fix possibly misleading documentation

* fix crash when integer out of bounds

* parse config string during initial processing

* use std::bind with length of list

* fix division by zero error

* use list_of

* change escaped_list_separator variable names

src/settings.h

@@ -93,6 +93,10 @@ struct Configuration
 
 	std::string pattern;
 
+	std::vector<size_t> playlist_editor_column_width_ratio;
+	std::vector<size_t> media_library_column_width_ratio_two;
+	std::vector<size_t> media_library_column_width_ratio_three;
+
 	std::vector<Column> columns;
 
 	DisplayMode playlist_display_mode;