(svn r6289) -Fix(r6108) : case 0x48 (generic text) should not have been set over newstations.

It grabbed everyting. Instead, we are now using ids for that purpose,  0xC9, oxD0, 0xDC (FS#304 by Osai)
- Protect newgrf text from entries of 1 char and fewer
- Protect currency name from an overrun of ids
Thanks to glx

newgrf_text.c

@@ -204,6 +204,9 @@ StringID AddGRFString(uint32 grfid, uint16 stringid, byte langid_to_add, bool ne
 	GRFText *newtext;
 	uint id;
 
+	/* We do not allow strings of only one char or even fewer*/
+	if (strlen(text_to_add) <= 1) return STR_EMPTY;
+
 	/* When working with the old language scheme (grf_version is less than 7) and
 	 * English or American is among the set bits, simply add it as English in
 	 * the new scheme, i.e. as langid = 1.