Remember ArticleView text size between app launches

Solves issue #230
Clean UnifiedDisplayView from irrelevant things
Fix UnifiedDisplayView text sizing

ArticleCellView must have the makeTextLarger, makeTextSmaller, canMakeTextLarger and canMakeTextSmaller methods.
We send these methods calls to one of the visible ArticleCellView.
Fix canGoForward (irrelevant)
Merge pull request #291 from barijaona/bugfixes

Improve "Bigger Text/Smaller Text" command
Restore and extend centering of article list cell’s content

Note : to be visible, animation must be started after the attributed string is drawn
Follow up on issue #277 (folder name centering)

For centering content of cells in folder list, use the technique already used for centering content of cells in article list.

Note : we had to transfer font assignment to -outlineView:objectValueForTableColumn:byItem:
instead of -outlineView:willDisplayCell:forTableColumn:item:. Otherwise, drawing the attributed string by ourself did not work.
Merge pull request #293 from barijaona/bugfixes

Vertically center text in the folder list and in the article list
Safety measure on GoogleReader

Cf Skripach crash logs at http://www.cocoaforge.com/viewtopic.php?f=18&t=26573&sid=38253d1334b27782d22d2f31daa258a9#p138418
Decode URLs for downloads
Safety measure for transactions ; improve refresh indicator

After seeing http://www.cocoaforge.com/viewtopic.php?f=18&t=26578
Serialize uses of the jsonDecoder

As recommended by JSONKit documentation
Use the jsonDecoder itself for serialization
Fix crash

As described at http://forums.cocoaforge.com/viewtopic.php?t=26583&p=138447
Fix crash 2

Crash caused by simultaneous attempts to update count of unread articles
http://forums.cocoaforge.com/viewtopic.php?f=18&t=26573
Crash prevention

Should two processes attempt to simultaneously update unread count
Merge pull request #294 from dcotton14/master

Decode URLs for enclosures (handle enclosures with spaces in name)
Merge pull request #295 from barijaona/bugfixes

Prevent some crashes
Remove a Xcode warning on dynamic library
setFlipped is deprecated
Just use the default NSFileManager