Shadow symbols NAMESTRING, NUMBER and INLINE in pgloader.parser package (#515)

Defining rules on standard symbols like CL:NAMESTRING is a bad idea
since other systems may do the same, inadvertently overwriting each
other's rules.

Furthermore, future esrap versions will probably prevent defining
rules whose names are symbols in locked packages, making this change
mandatory.

src/package.lisp

@@ -665,6 +665,7 @@
 (defpackage #:pgloader.parser
   (:use #:cl #:esrap #:metabang.bind
         #:pgloader.params #:pgloader.utils #:pgloader.sql #:pgloader.connection)
+  (:shadow #:namestring #:number #:inline)
   (:import-from #:alexandria #:read-file-into-string)
   (:import-from #:pgloader.sources
                 #:md-connection