Lua: Add lrexlib Rex to a submodule

std/lua/_std/EReg.hx

@@ -19,7 +19,7 @@
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  * DEALINGS IN THE SOFTWARE.
  */
-import lua.Rex;
+import lua.lrexlib.Rex;
 import lua.Table;
 import lua.Boot;
 

std/lua/Rex.hx → std/lua/lrexlib/Rex.hx

@@ -1,4 +1,4 @@
-package lua;
+package lua.lrexlib;
 @:luaRequire("rex_pcre")
 extern class Rex {