Use "clock rate"/"frequency" to describe CPU speed.
Check if emulator loaded file.
Formatting.
Disable RenderWindow framelimit.

Since we're ensuring the frame timings using a timer, any additional
delay caused by SFML doesn't affect the frame timings.
Merge pull request #25 from Ventero/fixes

Some minor nitpicks/fixes.
Merge pull request #26 from Ventero/framelimit

Disable RenderWindow framelimit.
Some type fixes and const correctness.