(refactor) logic required to calculate and perform a mouse click-and-drag.

+ simplify use of the array of elements on the "paper"
+ inline path variables (the fact that the values are "actual" and "expected" are implied in the expectation/assertion).
Now mouse even tracking accounts for the canvas' container padding.

+ without this, "paths" and other objects would appear shifted by the size of the padding.
+ included some refactoring.
Killed extraneous tests

+ also changed magic numbers to be prime.  I want to convey a sense of arbitrariness.  I also wish to encourage potential miscalculations.
+ connected up the translated path with the desired mouse path to make more explicit that the expected path is a direct translation of the drawn path.
(refactor) factor out logic to calculate relative position (within Raphael canvas) from absolute position (relative to HTML document).
(refactor) increase consistency of defining positions.

+ extract x and y values of positions into anonymous objects.  If we gave them a "class" they would be "Positions"
Removed useless part of error message for client unit tests.
WWP now renders a "draft line" as the user clicks-and-drags

+ refined how I specify test name strings (i.e. the values passed to describe() and it()) so that the output reads like a sentence.
+ first use of nested describe()s.
+ introduced method: pathAsArray to complement pathAsString.
Now, properly sets opacity when user lets go.
Initial line-drawing code is feature complete.