Add #appendTo()
Add some sensible defaults
Add #updateLoaded() method
Add #updateProgress() method
Require chrome, progress and knob imgs
Add example
Add drawing functions

One thing I probably need to add in the future is drawing the progress and
loaded bars from a specific percentage. Right now they start from 0, but
there are situations where we can load something starting from anywhere
inside [0,100].
Switch to using trough margins
Refactor duplicated logic
Attach mouse handlers
Add #onProgressUpdate()
Rename Slid => Slider
v0.1