add out of box features

[RodrigoDornelles]

tier 1

• [ ] os.execute
• [ ] io.output
• [ ] io.close
• [ ] io.read
• [ ] io.open
• [ ] io.write
• [ ] file:write
• [ ] file:read
• [ ] file:close

tier 2

• [ ] io.input
• [ ] io.lines
• [ ] file:lines
• [ ] io.stderr
• [ ] io.stdin
• [ ] io.stdout
• [ ] io.tmpfile
• [ ] io.type

tier3

• [ ] io.flush
• [ ] file:flush
• [ ] file:seek
• [ ] file:setvbuf