Lua page error handling cleanup

A little bit more warnings suppresed

Added additional artwork files for Retina Display Support

Better error handling and an include function for lua pages

Fix bugs about range request and explorer crashes

Lua docs

- Added mg.onerror, mg.include, mg.redirect
- mg.onerror, if overridden, lets the user trap syntax errors and
  other loadbuffer errors, and dump stack traces and debug info
  for uncaught runtime errors.
- Log unexpected errors from mg.onerror handlers
- Provide mg.cry so custom handlers can reproduce default behavior
- Call mg.onerror handler before unwinding stack
- If mg.onerror returns non-0, stop loading chunks
- Included pages stop parent page processing if mg.onerror returns non-zero
- Included pages don't sent HTTP errors, they throw lua errors