Fix BL-794 by keeping the cog at the bottom of the edit box.

We keep it there by adjusting the "bottom" property of the cog every time the scroll of the parent edit box changes.
Updated French Translation File from David Rowe
Fix BL-625, where imageInMiddle pages looked wrong when multilingual

The problem was that the CSS "calc" was failing because of lack of units on the SpaceBetweenMultilingualAlternatives variable.
Merge pull request #195 from BloomBooks/BL-794FormattingButtonPositioning

Fix BL-794 by keeping the cog at the bottom of the edit box.
Merge pull request #196 from BloomBooks/BL825ImageInMiddleCalculations

Fix BL-625, where imageInMiddle pages looked wrong when multilingual
Fix xmatter mixin that marked all cover pages as frontcover
Introduce less version of factory-xmatter, with no changes.