Various changes to bring pm.lua test closer to passing:

* New and complete character class support
 * string.gsub implemented
 * rawset implemented
 * lua_call added (based on lua_pcall)
 * lua_pop added
 * newCall removed; luaGetTable and luaSetTable in LFunction updated to
   use lua_call instead.
 * StandardTest changed to avoid an ArrayIndexOutOfBoundsException

Unfortunately I discovered a problem where execute() will loop around too
many times and call exec() with a call frame that has already completed.
This might be due to the lack of the "tailcalls" field in our CallInfo class
that the C version maintains?

src/test/res/strlib.lua

@@ -1,3 +1,7 @@
+print( string.find( 'alo alx 123 b\0o b\0o', '(..*) %1' ) )
+print( string.find( 'aloALO', '%l*' ) )
+print( string.find( ' \n isto <20> assim', '%S%S*' ) )
+
 print( string.find( "", "" ) )
 print( string.find( "ababaabbaba", "abb" ) )
 print( string.find( "ababaabbaba", "abb", 7 ) )
@@ -19,3 +23,23 @@ print( string.byte("hi", -3) )
 print( tostring(1234567890123) )
 print( tostring(1234567890124) )
 print( tostring(1234567890125) )
+
+function f1(s, p)
+  print(p)
+  p = string.gsub(p, "%%([0-9])", function (s) return "%" .. (s+1) end)
+  print(p)
+  p = string.gsub(p, "^(^?)", "%1()", 1)
+  print(p)
+  p = string.gsub(p, "($?)$", "()%1", 1)
+  print(p)
+  local t = {string.match(s, p)}
+  return string.sub(s, t[1], t[#t] - 1)
+end
+
+print( f1('alo alx 123 b\0o b\0o', '(..*) %1') )
+
+local function badpat()
+	print( string.gsub( "alo", "(.)", "%2" ) )
+end
+
+print( pcall( badpat ) )