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, 80 insertions, 0 deletions

diff --git a/lua/lexers/gnuplot.lua b/lua/lexers/gnuplot.lua
new file mode 100644
index 0000000..26913db
--- /dev/null
+++ b/lua/lexers/gnuplot.lua
@@ -0,0 +1,80 @@
+-- Copyright 2006-2016 Mitchell mitchell.att.foicica.com. See LICENSE.
+-- Gnuplot 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 = 'gnuplot'}
+
+-- 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("'")
+local dq_str = l.delimited_range('"')
+local bk_str = l.delimited_range('[]', true)
+local bc_str = l.delimited_range('{}', true)
+local string = token(l.STRING, sq_str + dq_str + bk_str + bc_str)
+
+-- Keywords.
+local keyword = token(l.KEYWORD, word_match{
+  'cd', 'call', 'clear', 'exit', 'fit', 'help', 'history', 'if', 'load',
+  'pause', 'plot', 'using', 'with', 'index', 'every', 'smooth', 'thru', 'print',
+  'pwd', 'quit', 'replot', 'reread', 'reset', 'save', 'set', 'show', 'unset',
+  'shell', 'splot', 'system', 'test', 'unset', 'update'
+})
+
+-- Functions.
+local func = token(l.FUNCTION, word_match{
+  'abs', 'acos', 'acosh', 'arg', 'asin', 'asinh', 'atan', 'atan2', 'atanh',
+  'besj0', 'besj1', 'besy0', 'besy1', 'ceil', 'cos', 'cosh', 'erf', 'erfc',
+  'exp', 'floor', 'gamma', 'ibeta', 'inverf', 'igamma', 'imag', 'invnorm',
+  'int', 'lambertw', 'lgamma', 'log', 'log10', 'norm', 'rand', 'real', 'sgn',
+  'sin', 'sinh', 'sqrt', 'tan', 'tanh', 'column', 'defined', 'tm_hour',
+  'tm_mday', 'tm_min', 'tm_mon', 'tm_sec', 'tm_wday', 'tm_yday', 'tm_year',
+  'valid'
+})
+
+-- Variables.
+local variable = token(l.VARIABLE, word_match{
+  'angles', 'arrow', 'autoscale', 'bars', 'bmargin', 'border', 'boxwidth',
+  'clabel', 'clip', 'cntrparam', 'colorbox', 'contour', 'datafile ',
+  'decimalsign', 'dgrid3d', 'dummy', 'encoding', 'fit', 'fontpath', 'format',
+  'functions', 'function', 'grid', 'hidden3d', 'historysize', 'isosamples',
+  'key', 'label', 'lmargin', 'loadpath', 'locale', 'logscale', 'mapping',
+  'margin', 'mouse', 'multiplot', 'mx2tics', 'mxtics', 'my2tics', 'mytics',
+  'mztics', 'offsets', 'origin', 'output', 'parametric', 'plot', 'pm3d',
+  'palette', 'pointsize', 'polar', 'print', 'rmargin', 'rrange', 'samples',
+  'size', 'style', 'surface', 'terminal', 'tics', 'ticslevel', 'ticscale',
+  'timestamp', 'timefmt', 'title', 'tmargin', 'trange', 'urange', 'variables',
+  'version', 'view', 'vrange', 'x2data', 'x2dtics', 'x2label', 'x2mtics',
+  'x2range', 'x2tics', 'x2zeroaxis', 'xdata', 'xdtics', 'xlabel', 'xmtics',
+  'xrange', 'xtics', 'xzeroaxis', 'y2data', 'y2dtics', 'y2label', 'y2mtics',
+  'y2range', 'y2tics', 'y2zeroaxis', 'ydata', 'ydtics', 'ylabel', 'ymtics',
+  'yrange', 'ytics', 'yzeroaxis', 'zdata', 'zdtics', 'cbdata', 'cbdtics',
+  'zero', 'zeroaxis', 'zlabel', 'zmtics', 'zrange', 'ztics', 'cblabel',
+  'cbmtics', 'cbrange', 'cbtics'
+})
+
+-- Identifiers.
+local identifier = token(l.IDENTIFIER, l.word)
+
+-- Operators.
+local operator = token(l.OPERATOR, S('-+~!$*%=<>&|^?:()'))
+
+M._rules = {
+  {'whitespace', ws},
+  {'keyword', keyword},
+  {'function', func},
+  {'variable', variable},
+  {'identifier', identifier},
+  {'string', string},
+  {'comment', comment},
+  {'operator', operator},
+}
+
+return M