Updating `dfhack.init-example` to enable UI plugins and add some keybindings

The UI plugins are one of the major reasons for most players to use dfhack, so they should be enabled by default.   The other additions seem to be semi-standard keybindings for those functions - see eg http://redd.it/2fuaaf

I'd also consider renaming the file `example-dfhack.init`, which is easier for many users to rename (it's also the same filetype as `dfhack.init`).