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, 62 deletions

diff --git a/lexers/desktop.lua b/lexers/desktop.lua
deleted file mode 100644
index 22c95f3..0000000
--- a/lexers/desktop.lua
+++ /dev/null
@@ -1,62 +0,0 @@
--- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
--- Desktop Entry 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 = 'desktop'}
-
--- Whitespace.
-local ws = token(l.WHITESPACE, l.space^1)
-
--- Comments.
-local comment = token(l.COMMENT, '#' * l.nonnewline^0)
-
--- Strings.
-local string = token(l.STRING, l.delimited_range('"'))
-
--- Group headers.
-local group_header = l.starts_line(token(l.STRING,
-                                         l.delimited_range('[]', false, true)))
-
--- Numbers.
-local number = token(l.NUMBER, (l.float + l.integer))
-
--- Keywords.
-local keyword = token(l.KEYWORD, word_match{'true', 'false'})
-
--- Locales.
-local locale = token(l.CLASS, l.delimited_range('[]', false, true))
-
--- Keys.
-local key = token(l.VARIABLE, word_match{
-  'Type', 'Version', 'Name', 'GenericName', 'NoDisplay', 'Comment', 'Icon',
-  'Hidden', 'OnlyShowIn', 'NotShowIn', 'TryExec', 'Exec', 'Exec', 'Path',
-  'Terminal', 'MimeType', 'Categories', 'StartupNotify', 'StartupWMClass', 'URL'
-})
-
--- Field codes.
-local code = l.token(l.CONSTANT, P('%') * S('fFuUdDnNickvm'))
-
--- Identifiers.
-local identifier = l.token(l.IDENTIFIER, l.alpha * (l.alnum + S('_-'))^0)
-
--- Operators.
-local operator = token(l.OPERATOR, S('='))
-
-M._rules = {
-  {'whitespace', ws},
-  {'keyword', keyword},
-  {'key', key},
-  {'identifier', identifier},
-  {'group_header', group_header},
-  {'locale', locale},
-  {'string', string},
-  {'comment', comment},
-  {'number', number},
-  {'code', code},
-  {'operator', operator},
-}
-
-return M