Update providers.xml

Some Russian ISP added
Adding missing Dutch translations
Update the Catalan translation and squeeze some of its strings.
Add SSL required for provider gmx.de (Issue 5876)
Merge pull request #358 from kiike/i18n-ca

Update the Catalan translation and squeeze some of its strings.
Merge pull request #356 from WebSpider/master

Adding missing Dutch translations
Merge pull request #350 from bboa/master

Update providers.xml to add a fairly comprehensive list of .ru mail providers.
Merge pull request #361 from aatdark/aatdark_issue5876

Add SSL required for provider gmx.de (Issue 5876)
Fix typo in res/values-nl/strings.xml
Skip incorrectly formatted/parsed LSUB/LIST replies

Example: * LIST (\HasChildren) "." [Folder]
"[Folder]" will be parsed as list containing the element "Folder".
Avoid race condition that can lead to a NullPointerException
Optimize code to extract the character to display in the fallback contact picture
Replace tabs with spaces