Don't change the value of equalalways

We were trying to avoid equalalways from changing the UI layout by
unsetting it and resetting it after changes. However, re-setting
equalalways actually resizes all the windows, so this never worked.

Instead we judiciously use rightbelow, leftabove, etc. and specify the
exact window sizes we want.

As a side-effect we make the terminal sizing a little more pleasant by
default, ensuring that it is no wider than 80 chars, and tries to use
any remianing vertical space after reserving 80 chars for the code
window.

python3/vimspector/debug_session.py

@@ -487,39 +487,39 @@ class DebugSession( object ):
     self._codeView = code.CodeView( code_window, self._api_prefix )
 
     # Call stack
-    with utils.TemporaryVimOptions( { 'splitright':  False,
-                                      'equalalways': False, } ):
-      vim.command( 'topleft vertical 50new' )
-      stack_trace_window = vim.current.window
-      self._stackTraceView = stack_trace.StackTraceView( self,
-                                                         self._connection,
-                                                         stack_trace_window )
+    vim.command( 'topleft vertical 50new' )
+    stack_trace_window = vim.current.window
+    one_third = int( vim.eval( 'winheight( 0 )' ) ) / 3
+    self._stackTraceView = stack_trace.StackTraceView( self,
+                                                       self._connection,
+                                                       stack_trace_window )
 
-    with utils.TemporaryVimOptions( { 'splitbelow':  False,
-                                      'eadirection': 'ver',
-                                      'equalalways': True } ):
-      # Watches
-      vim.command( 'new' )
-      watch_window = vim.current.window
+    # Watches
+    vim.command( 'leftabove new' )
+    watch_window = vim.current.window
 
-      # Variables
-      vim.command( 'new' )
-      vars_window = vim.current.window
+    # Variables
+    vim.command( 'leftabove new' )
+    vars_window = vim.current.window
 
-      self._variablesView = variables.VariablesView( self._connection,
-                                                     vars_window,
-                                                     watch_window )
+    with utils.LetCurrentWindow( vars_window ):
+      vim.command( f'{ one_third }wincmd _' )
+    with utils.LetCurrentWindow( watch_window ):
+      vim.command( f'{ one_third }wincmd _' )
+    with utils.LetCurrentWindow( stack_trace_window ):
+      vim.command( f'{ one_third }wincmd _' )
 
+    self._variablesView = variables.VariablesView( self._connection,
+                                                   vars_window,
+                                                   watch_window )
 
-    with utils.TemporaryVimOption( 'splitbelow', True ):
-      vim.current.window = code_window
-
-      # Output/logging
-      vim.command( '10new' )
-      output_window = vim.current.window
-      self._outputView = output.OutputView( self._connection,
-                                            output_window,
-                                            self._api_prefix )
+    # Output/logging
+    vim.current.window = code_window
+    vim.command( 'rightbelow 10new' )
+    output_window = vim.current.window
+    self._outputView = output.OutputView( self._connection,
+                                          output_window,
+                                          self._api_prefix )
 
     # TODO: If/when we support multiple sessions, we'll need some way to
     # indicate which tab was created and store all the tabs