Implement Lua ALE setup & overhaul documentation

1. Add ale.setup and ale.setup.buffer for pure Lua configuration.
2. Update many global settings to use Booleans instead of numbers to
   make types easiert to work with in Lua.
3. Radically reformat documentation and fix errors to make
   documentation more usable for Neovim users.

doc/ale-awk.txt

@@ -5,21 +5,27 @@ ALE Awk Integration                                           *ale-awk-options*
 ===============================================================================
 gawk                                                             *ale-awk-gawk*
 
-g:ale_awk_gawk_executable                           *g:ale_awk_gawk_executable*
+                                              *ale-options.awk_gawk_executable*
+                                                    *g:ale_awk_gawk_executable*
                                                     *b:ale_awk_gawk_executable*
+awk_gawk_executable
+g:ale_awk_gawk_executable
   Type: |String|
   Default: `'gawk'`
 
   This variable sets executable used for gawk.
 
-
-g:ale_awk_gawk_options                                 *g:ale_awk_gawk_options*
+                                                 *ale-options.awk_gawk_options*
+                                                       *g:ale_awk_gawk_options*
                                                        *b:ale_awk_gawk_options*
+awk_gawk_options
+g:ale_awk_gawk_options
   Type: |String|
   Default: `''`
 
-  With this variable we are able to pass extra arguments for gawk
-  for invocation.
+  With this variable we are able to pass extra arguments for gawk for
+  invocation.
+
 
 ===============================================================================
   vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl: