[amiwm] add a new command action to rotate windows

This adds a command to iterate over the set of windows.  It's not
like alt-tab in ye olde windows world where you'd alt tab once to
switch between two windows, and then keep alt-tab'ing with alt down
to go through the window list.  For now it just literally iterates
through those windows.

This makes it a lot easier to work with a large number of open
windows without having to constantly use the mouse.

MODULES.md

@@ -35,11 +35,13 @@ image, but repeated.
 ## Keyboard module
 
 With the Keyboard module, you can bind window manager functions to keys
-on the keyboard. The initstring should consist of keybindings on the
-form
+on the keyboard. The initstring should consist of one or more keybindings
+on the form
 
 modifiers<keysym>:where:func
 
+Multiple keybindings are specified with spaces between them.
+
 ### modifiers
 
 Modifiers is 0 or more of:
@@ -47,6 +49,10 @@ Modifiers is 0 or more of:
   Mod1 Mod2 Mod3 Mod4 Mod5
   Button1 Button2 Button3 Button4 Button5
 
+Modifiers are joined together using spaces.  This can be confusing
+as it looks like keybindings are specified with spaces between them
+but the parser actually handles this.
+
 The modifiers listed must be pressed together with the key to activate
 the binding.
 
@@ -67,6 +73,8 @@ The function to perform when the key is pressed.
 Currently the following are defined:
 
 rotatescreens  -  Move the frontmost screen to the back
+raisewindow    -  Rotate the bottom window to the top of the screen
+lowerwindow    -  Rotate the top window to the bottom of the screen
 front          -  Move the window in which the key is pressed to the front
 back           -  Move the window in which the key is pressed to the back
 iconify        -  Iconify the window in which the key is pressed
@@ -84,6 +92,13 @@ iconify respectively.  The will only have effect inside windows and in
 window frames.  (These are the only places that front/iconfy/back has
 effect anyway.)
 
+An example with multiple modifiers in a single keybinding.
+
+Module "Keyboard" \
+	Meta<M>:all:rotatewindows\
+	Meta<Tab>:all:raisescreen\
+	Control Meta<Tab>:all:lowerscreen"
+
 ## Filesystem module
 
 This is an april fools joke module, but at least it's a starting