Wren TIC.btn fixes

[txgruppi]

The fixes

Two fixes for the Wren's API

1. TIC.btn() was not defined in Wren and had the wrong return value
2. TIC.btn(_) was mixing controllers 1 & 3, 2 & 4

TIC.btn()

Fixed 2 problems:

1. The handler wren_btn was checking for this call but it was not declared as part of the TIC class and it was not defined in foreignTicMethods
2. The handler wren_btn was setting the return value to bool instead of double

TIC.btn(_)

The button index bitmask was 0xf instead of 0x1f, this made tat gamepad 3 returned value for gamepad 1 and gamepad 4 returned value for gamepad 2.

[nesbox]

Looks good.
Thank you.