GenerateManpage: greatly simplify the code

We can take advantage of modern Pandoc features to move information like the
release date, the man page section, etc. into the markdown source rather than
having to insert that data during the rendering process. The only thing that
remains to be figured out by this tool is the set of known key bindings.

man/xmonad.1.markdown

@@ -1,7 +1,12 @@
-#Name
-xmonad - a tiling window manager
+% XMONAD(1) Tiling Window Manager
+%
+% 20 August 2018
 
-#Description
+# Name
+
+xmonad - Tiling Window Manager
+
+# Description
 
 _xmonad_ is a minimalist tiling window manager for X, written in Haskell.
 Windows are managed using automatic layout algorithms, which can be
@@ -28,7 +33,7 @@ combination of static guarantees provided by the type system, and
 type-based automated testing. A benefit of this is that the code is simple
 to understand, and easy to modify.
 
-#Usage
+# Usage
 
 _xmonad_ places each window into a "workspace". Each workspace can have
 any number of windows, which you can cycle though with mod-j and mod-k.
@@ -47,7 +52,8 @@ starts, workspace 1 is on screen 1, workspace 2 is on screen 2, etc. When
 switching workspaces to one that is already visible, the current and
 visible workspaces are swapped.
 
-##Flags
+## Flags
+
 xmonad  has  several flags which  you may pass to the executable.
 These flags are:
 
@@ -70,12 +76,13 @@ These flags are:
 
 ___KEYBINDINGS___
 
-#Examples
+# Examples
+
 To use xmonad as your window manager add to your _~/.xinitrc_ file:
 
 > exec xmonad
 
-#Customization
+# Customization
 xmonad is customized in ~/.xmonad/xmonad.hs, and then restarted
 with mod-q.
 
@@ -83,7 +90,7 @@ You can find many extensions to the core feature set in the xmonad-
 contrib package, available through your  package  manager  or  from
 [xmonad.org].
 
-##Modular Configuration
+## Modular Configuration
 As of _xmonad-0.9_, any additional Haskell modules may be placed in
 _~/.xmonad/lib/_ are available in GHC's searchpath. Hierarchical modules
 are supported: for example, the file
@@ -97,7 +104,7 @@ module XMonad.Stack.MyAdditions (function1) where
 Your xmonad.hs may then import XMonad.Stack.MyAdditions as if that
 module was contained within xmonad or xmonad-contrib.
 
-#Bugs
+# Bugs
 Probably. If you find any, please report them to the [bugtracker]
 
 [xmonad.org]: http://xmonad.org