REFACTOR [a vs an]

From /dev/humancontroller.

code/botlib/l_precomp.h

@@ -117,7 +117,7 @@ int PC_ExpectTokenType(source_t *source, int type, int subtype, token_t *token);
 int PC_ExpectAnyToken(source_t *source, token_t *token);
 //returns true when the token is available
 int PC_CheckTokenString(source_t *source, 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 PC_CheckTokenType(source_t *source, int type, int subtype, token_t *token);
 //skip tokens until the given token string is read
 int PC_SkipUntilString(source_t *source, char *string);