Improved UnifiedDisplayView

If we detect a dimension problem, we have to wait a while until the different dimensions get coherent. This also allows us to remove the horrible hack that was needed with initial app launch : there isn't cell size problem with the standard style (Tyger graphite) and launch with a single tab.
Simplified and more efficient didFailLoadWithError WebView delegate method.
Fix a problem with the french version of the Enclosure panel

As reported by user sandstrom at http://forums.cocoaforge.com/viewtopic.php?f=18&t=26342
Get more articles in OpenReader

We can now do it as OpenReader fixed https://github.com/feedhq/feedhq/issues/62
Still working on UnifiedDisplayView

- set earlier the inProgress property for ArticleCellView
- make sure we have an ArticleCellView before performing certain actions
UnifiedDisplayView improvement

- check if we are working on the cell known by the PXListView object for the row
- detect when there is already another cell being drawn for the row
…
Silence some warnings
Replace deprecated file related routines
Fix OS X Mavericks/Xcode 5 "about:blank" problem

When building with Xcode 5 on an OS X Mavericks(10.9) system, the user got many annoying "there is no application set to open the URL about:blank" alert dialogs.
Safety measure for handling articles in list views.

Should handle issue #232
Fix a leak
Fix a static analyzer error
Some changes suggested by Xcode 5
Improved safeguard of the list of open tabs

Bug described at http://forums.cocoaforge.com/viewtopic.php?t=26391&p=137525
Tabs should be opened before being saved.
Handle situations where OpenReader server is down

"Refresh all subscriptions" is now able to refresh at least the local feeds when the OpenReader server is down.
Improved UnifiedDisplayView
Subtler indicator for OpenReader feeds
Merge pull request #233 from barijaona/bugfixes

Different bug fixes and improvements : most work was on Unified display view
Upgrade version number to 3.0.0 Beta 19