[+-] support for settings

ChangeLog

@@ -2,6 +2,7 @@
 date:
 	* version 0.4
 	* added :edit, :e and :tabedit aliases for :open, :tabopen
+	* settings can now be changed with += and -= like in vim (patch from Виктор Кожухаров)
 	* :open without argument reloads current page, :tabopen opens an empty tab
 	* added 'n' and 'N' to repeat a search