Support the lldb debugger

The advantage of this one is that it has globals and statics in the
variables and runs directly in lldb. It can also show disassembly,
though we don't yet support that.

The disadvantage is that this is yet another plugin that plays fast and
loose with the protocol, so we have to add a bunch more gets.

python3/vimspector/output.py

@@ -27,7 +27,7 @@ class OutputView( object ):
     self.ShowOutput( 'stdout' )
 
   def OnOutput( self, event ):
-    category = event[ 'category' ]
+    category = event.get( 'category' ) or 'output'
     if category not in self._buffers:
       self._CreateBuffer( category )