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, 29 insertions, 0 deletions

diff --git a/lua/lexers/rhtml.lua b/lua/lexers/rhtml.lua
new file mode 100644
index 0000000..3886e20
--- /dev/null
+++ b/lua/lexers/rhtml.lua
@@ -0,0 +1,29 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- RHTML 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 = 'rhtml'}
+
+-- Embedded in HTML.
+local html = l.load('html')
+
+-- Embedded Ruby.
+local ruby = l.load('rails')
+local ruby_start_rule = token('rhtml_tag', '<%' * P('=')^-1)
+local ruby_end_rule = token('rhtml_tag', '%>')
+l.embed_lexer(html, ruby, ruby_start_rule, ruby_end_rule)
+
+M._tokenstyles = {
+  rhtml_tag = l.STYLE_EMBEDDED
+}
+
+local _foldsymbols = html._foldsymbols
+_foldsymbols._patterns[#_foldsymbols._patterns + 1] = '<%%'
+_foldsymbols._patterns[#_foldsymbols._patterns + 1] = '%%>'
+_foldsymbols.rhtml_tag = {['<%'] = 1, ['%>'] = -1}
+M._foldsymbols = _foldsymbols
+
+return M