implementing a later coming fallback to disco rather easy.

Caps is now used for: File Transfers, MUC Invites, Ad-Hoc Commands.

TODO:
 * Also handle it this way for typing notifications
   (This might give some trouble / compatibility issues)
 * Fall back to service discovery if no caps are available. Otherwise,
   we break compatibility with a lot of clients. (Asterix?)

This also fixes the problem of showing the wrong icon when expanding metacontacts.

Example:
We have the groups A, B, C in our child model
But only A and C are visible (and therefore in modelfilter)

Imagine we have a childIter_G pointing to group B
Getting its path in the childmodel, will give us (lets say) 2
2 means now the second group/row in the CHILD model
We now pass this to the tree and tell him "Expand row 2"
The tree itself is looking at the 2nd row of modelfilter: "Hey modelfilter, expand row number 2"

For modelfilter row number 2 is C and NOT B

We are not absolutely sure why some things are happening. Maybe that will help tracing the strange bugs.

This isn't an easy fix, we need to stop using expat in namespace aware
mode.

Fixes #3083. I can't believe this was unfixed for so long, as it's
really a rather easy fix.

Close preset messages popup before closing the status window. Otherwise GTK will freeze when the window is closed after the inactivity timer has expired. Fixes #4052

* configure --help to show disable message when --disable-FEATURES (we can use disable or enable
for each one AFAIK)
* Add dbus compile time requirement to README.html

URLs like (http://myFoobar.org) and http://en.wikipedia.org/wiki/Mornington_Crescent_(game) are now correctly detected.

Do not update metacontacts when nothing has changed. Fixes sending metacontact info to server when we expand a groupchat.

 * Do not double escape group names
 * Try to remove SelfContact on disconnect only once
 * Do not show minimized groupchats which were minimized after disconnect
 * Always reset group expand state after adding a contact to roster.

don't try the old (XEP-018) way to go invisible. It's not XMPP complient. That prevent to show the we are invisible but we are not. Fixes #4012

don't think connection to server failed when only first connection attempt failed when creating a new account