filename shortening needs file extension to make decisions.
closes #PICARD-613
Merge pull request #344 from xlotlu/master

filename shortening needs file extension to make decisions.
Fix evaluation of script functions with zero arguments.
Fixed plugin precedence for the first plugin in plugin list.

If a plugin was in both the system wide and ther user's plugin folder and the plugin was the first in the list the plugin was loaded and listed twice.
Load the options dialog even if there is a ScriptError.

Before a ScriptError, which is rasied for e.g. a missing function, the options dialog would not show up. This prevents the user from even fixing the scripting.
Merge pull request #346 from phw/plugin-fixes

Fixed plugin precedence for the first plugin in plugin list.
Merge pull request #347 from phw/fix-load-options-on-script-error

Load the options dialog even if there is a ScriptError.
Update picard.pot file
Update translation files
Better fix for script functions with zero arguments.
Merge pull request #345 from phw/fix-script-function-with-zero-arguments

Fix evaluation of script functions with zero arguments.
Adding download plugin functionality to existing UI

A list of plugins (JSON) is downloaded when Picard starts. The JSON
data is used to match already present plugins with those on the server.

The result is something like this: http://i.imgur.com/cL8VuM5.jpg

The entries checked are the plugins that are enabled. The ones in the
bold are those which are available for download, i.e, they are
present on our Github Repo. Those not bold might have been added by the
user from other means (such as by copying plugin files to Picard's
directory.)

One thing that worries me about the bold ones is that as plugins get
added to the GH repo, most of the entries in the list will be bold, and
that won't look good.

All the user has to do is select one in the bold and press the "Download
Plugin" button (that part isn't finished yet.)

The data used to check if the plugins are on our Github repo or not is here:
https://raw.githubusercontent.com/dufferzafar/picard-plugins/master/Plugins.json

The script used to generate the JSON and a API that helps with downloads are here:
https://github.com/dufferzafar/picard-plugins

Apart from the actual download, the one thing that still needs to be
done is listing the plugins that are on Github but not present in plugin
folders.