- updated the CAT CW stuff, now maintaining a ring buffer.

- updated the CAT CW stuff, now maintaining a ring buffer.
  Several corrections such that hitting a "local" CW key aborts
  CAT CW correctly and continues with manual CW.

- moved choice of active level for CW buttons to GPIO menu

- added support for "CW letter spacing" in CW menu

- at many places corrected cast from a generic pointer to int. The correct
  way of passing an int when receiving a pointer is:

  void extern(void *p) {
    int state=(uintptr_t) p;
    call intern(state);
  }

  What is certainly wrong is "call intern((uintptr_t) p)" since this
  passes on many systems a 64-bit value where a 32-bit value is expected
  unless strong prototyping is used.

- cleaned up configure.c (at least: "gtk_widget_destroy(dialog)" in configure_gpio
  had to be deleted)

- use cw_breakin instead of vox_hang in CW-keyer

- improved GPIO side tone creation, no longer use softTone but do this within the keyer thread
  (but only if GPIO side tone is requested).

- Hide button names such as CWL_BUTTON from iambic.c

- Major overhaul of iambic keyer: see extensive comment in iambic.c