REFACTOR [a vs an]

From /dev/humancontroller.

code/botlib/l_script.h

@@ -201,7 +201,7 @@ int PS_ExpectTokenType(script_t *script, int type, int subtype, token_t *token);
 int PS_ExpectAnyToken(script_t *script, token_t *token);
 //returns true when the token is available
 int PS_CheckTokenString(script_t *script, char *string);
-//returns true an reads the token when a token with the given type is available
+//returns true and reads the token when a token with the given type is available
 int PS_CheckTokenType(script_t *script, int type, int subtype, token_t *token);
 //skip tokens until the given token string is read
 int PS_SkipUntilString(script_t *script, char *string);