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, 58 deletions

diff --git a/lexers/bibtex.lua b/lexers/bibtex.lua
deleted file mode 100644
index b47770c..0000000
--- a/lexers/bibtex.lua
+++ /dev/null
@@ -1,58 +0,0 @@
--- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
--- Bibtex 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 = 'bibtex'}
-
--- Whitespace.
-local ws = token(l.WHITESPACE, l.space^1)
-
--- Strings.
-local string = token(l.STRING, l.delimited_range('"') +
-                               l.delimited_range('{}', false, true, true))
-
--- Fields.
-local field = token('field', word_match{
-  'author', 'title', 'journal', 'year', 'volume', 'number', 'pages', 'month',
-  'note', 'key', 'publisher', 'editor', 'series', 'address', 'edition',
-  'howpublished', 'booktitle', 'organization', 'chapter', 'school',
-  'institution', 'type', 'isbn', 'issn', 'affiliation', 'issue', 'keyword',
-  'url'
-})
-
--- Identifiers.
-local identifier = token(l.IDENTIFIER, l.word)
-
--- Operators.
-local operator = token(l.OPERATOR, S(',='))
-
-M._rules = {
-  {'whitespace', ws},
-  {'field', field},
-  {'identifier', identifier},
-  {'string', string},
-  {'operator', operator},
-}
-
--- Embedded in Latex.
-local latex = l.load('latex')
-
--- Embedded Bibtex.
-local entry = token('entry', P('@') * word_match({
-  'book', 'article', 'booklet', 'conference', 'inbook', 'incollection',
-  'inproceedings', 'manual', 'mastersthesis', 'lambda', 'misc', 'phdthesis',
-  'proceedings', 'techreport', 'unpublished'
-}, nil, true))
-local bibtex_start_rule = entry * ws^0 * token(l.OPERATOR, P('{'))
-local bibtex_end_rule = token(l.OPERATOR, P('}'))
-l.embed_lexer(latex, M, bibtex_start_rule, bibtex_end_rule)
-
-M._tokenstyles = {
-  field = l.STYLE_CONSTANT,
-  entry = l.STYLE_PREPROCESSOR
-}
-
-return M