Move the output window to its own space

And separate all the different channels into their own buffers. Use the
WinBar to select between them.

python3/vimspector/output.py

@@ -0,0 +1,58 @@
+# vimspector - A multi-language debugging system for Vim
+# Copyright 2018 Ben Jackson
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from vimspector import utils
+
+import vim
+
+
+class OutputView( object ):
+  def __init__( self, window ):
+    self._window = window
+    self._buffers = {}
+
+    self._CreateBuffer( 'stdout' )
+    self.ShowOutput( 'stdout' )
+
+  def OnOutput( self, event ):
+    category = event[ 'category' ]
+    if category not in self._buffers:
+      self._CreateBuffer( category )
+
+    with utils.ModifiableScratchBuffer( self._buffers[ category ] ):
+      self._buffers[ category ].append( event[ 'output' ].splitlines() )
+
+  def Clear( self ):
+    for buf in self._buffers:
+      self._buffers[ buf ] = None
+
+  def ShowOutput( self, category ):
+    vim.current.window = self._window
+    vim.command( 'bu {0}'.format( self._buffers[ category ].name ) )
+
+  def _CreateBuffer( self, category ):
+    with utils.RestorCurrentWindow():
+      vim.current.window = self._window
+
+      vim.command( 'enew' )
+      self._buffers[ category ] = vim.current.buffer
+      self._buffers[ category ].append( category + '-----' )
+
+      utils.SetUpHiddenBuffer( self._buffers[ category ],
+                               'vimspector.Output:{0}'.format( category ) )
+
+      vim.command( "nnoremenu WinBar.{0} "
+                   ":call vimspector#ShowOutput( '{0}' )<CR>".format(
+                     utils.Escape( category ) ) )