Add PCRE to support regular expressions

Use regular expressions instead of Lua patterns for find and replace editor commands.

Syntax files can now use regex or Lua patterns as before keeping backward compatibility for plugins.

data/core/commands/findreplace.lua

@@ -90,6 +90,7 @@ local function has_selection()
      and core.active_view.doc:has_selection()
 end
 
+
 command.add(has_selection, {
   ["find-replace:select-next"] = function()
     local l1, c1, l2, c2 = doc():get_selection(true)
@@ -107,9 +108,9 @@ command.add("core.docview", {
     end)
   end,
 
-  ["find-replace:find-pattern"] = function()
-    find("Find Text Pattern", function(doc, line, col, text)
-      local opt = { wrap = true, no_case = true, pattern = true }
+  ["find-replace:find-regex"] = function()
+    find("Find Text Regex", function(doc, line, col, text)
+      local opt = { wrap = true, no_case = true, regex = true }
       return search.find(doc, line, col, text, opt)
     end)
   end,
@@ -144,9 +145,10 @@ command.add("core.docview", {
     end)
   end,
 
-  ["find-replace:replace-pattern"] = function()
-    replace("Pattern", "", function(text, old, new)
-      return text:gsub(old, new)
+  ["find-replace:replace-regex"] = function()
+    replace("Regex", "", function(text, old, new)
+      local re = regex.compile(old)
+      return regex.gsub(re, text, new)
     end)
   end,