Move all lua related files to lua/ subfolder

Also remove the lexers sub directory from the Lua search path.
As a result we attempt to open fewer files during startup:

 $ strace -e open -o log ./vis +q config.h && wc -l log

In order to avoid having to modifiy all lexers which `require('lexer')`
we instead place a symlink in the top level directory.

 $ ./configure --disable-lua
 $ rm -rf lua

Should result in a source tree with most lua specifc functionality
removed.

2 files changed, 0 insertions, 51 deletions

diff --git a/luadoc/README.md b/luadoc/README.md
deleted file mode 100644
index 17531da..0000000
--- a/luadoc/README.md
+++ /dev/null
@@ -1,37 +0,0 @@
-This is the destination directory for the LDoc documentation of Vis' Lua API
-as generated by the `make luadoc`.
-
-Unfortunately `ldoc(1)` seems to have a bug which generates broken reference
-links for custom types. The following patch seems to fix the issue:
-
-```
-From 96a1fbc8e972fedf665049a6351f46bc1aac1768 Mon Sep 17 00:00:00 2001
-From: =?UTF-8?q?Marc=20Andr=C3=A9=20Tanner?= <mat@brain-dump.org>
-Date: Tue, 6 Dec 2016 15:59:17 +0100
-Subject: [PATCH] Fix references to class types.
-
-For classes the generated HTML anchors need to be prefixed 'Class_'.
----
- ldoc/doc.lua | 6 +++---
- 1 file changed, 3 insertions(+), 3 deletions(-)
-
-diff --git a/ldoc/doc.lua b/ldoc/doc.lua
-index e19b2df..f368b90 100644
---- a/ldoc/doc.lua
-+++ b/ldoc/doc.lua
-@@ -1073,9 +1073,9 @@ end
- local function reference (s, mod_ref, item_ref)
-    local name = item_ref and item_ref.name or ''
-    -- this is deeply hacky; classes have 'Class ' prepended.
----~    if item_ref and doc.class_tag(item_ref.type) then
----~       name = 'Class_'..name
----~    end
-+       if item_ref and doc.class_tag(item_ref.type) then
-+          name = 'Class_'..name
-+       end
-    return {mod = mod_ref, name = name, label=s}
- end
- 
--- 
-1.9.1
-```
diff --git a/luadoc/config.ld b/luadoc/config.ld
deleted file mode 100644
index 8567a89..0000000
--- a/luadoc/config.ld
+++ /dev/null
@@ -1,14 +0,0 @@
--- Configuration file for Luadoc API generation
-project="Vis Editor"
-title="Vis Editor Lua API documentation"
-format="markdown"
-style="!fixed"
-dir="."
-sort=true
-merge=true
-no_space_before_args=true
-file={
-	"../vis-lua.c",
-	"../vis.lua",
-}
-	
\ No newline at end of file