Added file-header pattern support to syntax

data/plugins/language_lua.lua

@@ -2,6 +2,7 @@ local syntax = require "core.syntax"
 
 syntax.add {
   files = "%.lua$",
+  headers = "^#!.*[ /]lua",
   comment = "--",
   patterns = {
     { pattern = { '"', '"', '\\' },       type = "string"   },

data/plugins/language_python.lua

@@ -2,6 +2,7 @@ local syntax = require "core.syntax"
 
 syntax.add {
   files = "%.py$",
+  headers = "^#!.*[ /]python",
   comment = "#",
   patterns = {
     { pattern = { "#", "\n" },            type = "comment"  },

data/plugins/language_xml.lua

@@ -2,6 +2,7 @@ local syntax = require "core.syntax"
 
 syntax.add {
   files = { "%.xml$", "%.html?$" },
+  headers = "<%?xml",
   patterns = {
     { pattern = { "<!%-%-", "%-%->" },     type = "comment"  },
     { pattern = { '%f[^>][^<]', '%f[<]' }, type = "normal"   },