Fixed some typos preventing synthesys
Updated dtg.v to use my current naming scheme
Added pixel clock IP
 Added logo and empty tile block ROM coefficient files
Added Logo ROM IP
 Added empty tile ROM IP
Added top level (in video_subsystem) strictly for pwl's testing
Implemented printing the Logo and blank tile functionality
Merge branch 'master' of https://github.com/jfluth/porcupineApple