Allow passing single IDs when calling external scripts

BUTTON is documented to pass the UUIDs of the controller *and* the sitter when they are different, separated by a "|".

ADJUST is not documented to do that (yet), but it behaves that way.

Both behaviours are undesirable for generic scripts that respond to a link message without being specifically designed for AVsitter, because they don't expect the extra UUID. This can be seen as an AVsitter shortcoming, therefore we implement backwards-compatible workarounds.

For ADJUST, the AMENU argument's range has been extended:

  0, 1 and 2 behave the same as before.
  4, 5 and 6 behave as 0, 1 and 2 respectively, but also inhibit sending the second UUID.

For BUTTON, two special values have been added for the ID field: <C> and <S>, which will be replaced with CONTROLLER and SITTER respectively. For example:

    BUTTON text|num|str

behaves the same as before, sending both CONTROLLER and SITTER in the UUID field when they differ; however:

    BUTTON text|num|str|<C>

always passes only the UUID of the person who controls the menu. Similarly for <S>.

AVsitter2/[AV]sitB.lsl

@@ -278,6 +278,10 @@ default
             if (llGetListLength(button_data) > 2)
             {
                 id = llList2String(button_data, 2);
+                if (id == "<C>")
+                    id = CONTROLLER;
+                if (id == "<S>")
+                    id = MY_SITTER;
             }
             else if (CONTROLLER != MY_SITTER)
             {