Changes that affect the user interface

Changes that affect the user interface
======================================

A. applies only if compiled with the STEMLAB_DISCOVERY_OPTION:
   unified non-AVAHI and AVAHI versions of stemlab_discovery.
   STEMLAB_DISCOVERY_MAC in Makefile.mac no longer needed.
   Made the user interface more specific in the NO_AVAHI version.
   Currently, the no-avahi version is only activated in Makefile.mac
   but could be useful for *nix systems where you do not have avahi.

B. applies only if compiled with SPLIT_RXTX defined:
  if using two receivers, the TX panel only "hides" the first one.
  it is possible to listen to RX2 while TXing on the RX1 frequency,
  very useful for measurements where you feed-back the attenuated
  TX signal to the RX2 antenna jack. This implies that if RX2
  is active while TXing, you see the S-meter of RX2 and not the
  TX levels (to be able to measure the signal strength).
  RXing with RX2 and TXing with TX on the RX1 frequency implies
  that you go "split".
  This is so useful that it is the default option for me now.

C. applies only if compiled with DIGI_MODES defined:
   when switching to DIGU or DIGL, you automatically get wide
   RX filters (0 ... 3000 Hz) and all noise reduction OFF
   without changing the current settings. So when returning to
   another mode (say, CWL or USB), the filter/NR settings
   effective before switching to digi are restored.
  This is so useful that it is the default option for me now.

D. if *not* compiled with the PURESIGNAL_OPTION, you still get
   a two-tone generator for testing purposed. The new button
   TT is located exactly where the PS button is placed if
   compiled with PURESIGNAL.

E. Small change to make B. meaningful:
   - Upon TX, mute only that RX that is bound to the TX frequency
   - Upon TX, mute the audio of the active_receiver only in CW mode
     (to give room for the side tone).

Error corrections (only the most important ones)
================================================

  - avoid core dump if using PURESIGNAL with METIS devices:
    create receiver[PS_T(R)X_FEEDBACK] in any case

  - colouring the correct TX frequency in red in the VFO panel

  - use correct attenuation scale for filter_board == CHARLY25

  - initialize tx->attenuation

  - explicitly specifying levels and frequencies for two-tone
    (the defaults were silently used).

  - changed an #ifdef FREEDV to #ifdef PURESIGNAL in vfo_menu.c (obvious error)