Externalize Pattern Generation

[samt]

Take all pattern generation code and place it into a function to generate it.

Should have this prototype:

/*
 * @param String|Array sequence - Sequence of compatible characters for encoding
 * @param String|Int checkdigit - calculated check digit
 * @return Array<Int> - Array of bar/space widths (alternating, starting with bar)
 */
function generateSequence(sequence, checkdigit) { }