add switch-to-last-tab in pentadactyl

pentadactyl/pentadactylrc

@@ -29,5 +29,8 @@ map K <C-u>
 map l gt
 map h gT
 
+" screen/tmux-like switch to previous tab
+map <C-a><C-a> <C-^>
+
 " reload pentadactylrc
 map <C-r> :source ~/.pentadactylrc<CR>:echo "Configuration Reloaded (~/.pentadactylrc)"<CR>