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.

1 files changed, 0 insertions, 56 deletions

diff --git a/lexers/gap.lua b/lexers/gap.lua
deleted file mode 100644
index 3d9f7a4..0000000
--- a/lexers/gap.lua
+++ /dev/null
@@ -1,56 +0,0 @@
--- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
--- Gap LPeg lexer.
-
-local l = require('lexer')
-local token, word_match = l.token, l.word_match
-local P, R, S = lpeg.P, lpeg.R, lpeg.S
-
-local M = {_NAME = 'gap'}
-
--- Whitespace.
-local ws = token(l.WHITESPACE, l.space^1)
-
--- Comments.
-local comment = token(l.COMMENT, '#' * l.nonnewline^0)
-
--- Strings.
-local sq_str = l.delimited_range("'", true)
-local dq_str = l.delimited_range('"', true)
-local string = token(l.STRING, sq_str + dq_str)
-
--- Numbers.
-local number = token(l.NUMBER, l.digit^1 * -l.alpha)
-
--- Keywords.
-local keyword = token(l.KEYWORD, word_match{
-  'and', 'break', 'continue', 'do', 'elif', 'else', 'end', 'fail', 'false',
-  'fi', 'for', 'function', 'if', 'in', 'infinity', 'local', 'not', 'od', 'or',
-  'rec', 'repeat', 'return', 'then', 'true', 'until', 'while'
-})
-
--- Identifiers.
-local identifier = token(l.IDENTIFIER, l.word)
-
--- Operators.
-local operator = token(l.OPERATOR, S('*+-,./:;<=>~^#()[]{}'))
-
-M._rules = {
-  {'whitespace', ws},
-  {'keyword', keyword},
-  {'identifier', identifier},
-  {'string', string},
-  {'comment', comment},
-  {'number', number},
-  {'operator', operator},
-}
-
-M._foldsymbols = {
-  _patterns = {'[a-z]+', '#'},
-  [l.KEYWORD] = {
-    ['function'] = 1, ['end'] = -1, ['do'] = 1, od = -1, ['if'] = 1, fi = -1,
-    ['repeat'] = 1, ['until'] = -1
-  },
-  [l.COMMENT] = {['#'] = l.fold_line_comments('#')}
-}
-
-return M