initial calculations with width on clip
don't let thumbnail fall off player if sprite uses clip
Add a width option per time signature
This width option is used so that we can figure out whether the
thumbnail will fall off the player or not.
Also, move setting 'left' to after we get the mouseTime so we get the
proper mouseTime setting.
Use settings[mouseTime].width for visible width
If the above option is available, use that. Otherwise, try and get it
from the initial setting: settings[0].
Also, rename 'getWidth' to 'getVisibleWidth'.
Update README
Merge pull request #17 from brightcove/fallingoff

Don't let thumbnail fall off player