getWidthFactor() tests the wrong value for synthetic spread

[danielweck]

getWidthFactor() tests readerSettings.syntheticSpread for "double", but does not take into account the default case "auto" as per the synthetic spread decision grid:

http://docs.google.com/spreadsheet/ccc?key=0AoPMUkQhc4wcdDI0anFvWm96N0xRT184ZE96MXFRdFE&usp=drive_web#gid=0

Which is implemented here:
https://github.com/readium/readium-shared-js/blob/develop/js/helpers.js#L207

This results in the value of left/right spacing changing when switching from auto to double, yet in both cases the reader is in synthetic spread view.

getWidthFactor():
https://github.com/readium/readium-js-viewer/blob/develop/lib/ReaderSettingsDialog.js#L27

Related issue: #103

[danielweck]

Addressed in "textWidthMargins" feature branch (code in readium-share-js so native launchers also work):
https://github.com/readium/readium-js-viewer/tree/feature/textWidthMargins
https://github.com/readium/readium-shared-js/tree/feature/textWidthMargins

[danielweck]

Fixed by Pull Request:
readium/readium-shared-js#93
readium/readium-js#68
#151