Name peep variables for current train and car
Fix finding peep on ride news items

Peep's current_* variables were offset by 1. Also fixed comparison
between 32-bit and 16-bit ints.
Change peep news item enum names
Add rct_car sprite and tidy up news locator

Also add (x,y,z) coordinate variables for rct_peep
Fix comments
fix case and add author to source code header