Merging most of the changes and refactoring from version V3

[mrkusypl]

Hello.

After many hours of struggling to figure out why the Basic version exceeds the size limit, I would like to present this pull request, which includes the vast majority of the bug fixes and changes made in version V3.

Before I start listing the changes made to the code, I want to mention that I DON'T HAVE THE V1 VERSION OF THE RADIO... I have no way to test the changes, so I'll have to leave that up to you. I doubt anything won't work, but it's always worth checking.

Changelog

• Major code optimization (536 bytes saved): armel/uv-k1-k5v3-firmware-custom@28500e1

• Major code refactoring: armel/uv-k1-k5v3-firmware-custom@e28177c

• Enable beeps for Aircopy, minor code refactoring: armel/uv-k1-k5v3-firmware-custom@7c343a2

• Code refactoring; improvements to K5Viewer and the UI: armel/uv-k1-k5v3-firmware-custom@9574376
  As for K5Viewer, I only migrated SetInv.

• Reduce the lag between consecutive RX on both frequencies under DW mode (issue # 198): armel/uv-k1-k5v3-firmware-custom@d826cbd

• Fix SCAN_SAVE_CHANNEL and UI_GenerateChannelStringEx: armel/uv-k1-k5v3-firmware-custom@85f1bfd
  No changes to the 4-digit channel number

• Fix Bandscope + Game: armel/uv-k1-k5v3-firmware-custom@c901b2e

• Fix breakout: reliable key handling from K5Viewer (issue armel#214): armel/uv-k1-k5v3-firmware-custom@f5d6f57
  No changes regarding the key handling from K5Viewer

• FM_CheckFrequencyLock() refactoring: armel/uv-k1-k5v3-firmware-custom@d9eb55f

• Fix issue # 40: armel/uv-k1-k5v3-firmware-custom@0ddbb0a

• Fix MR channel persistence when entered with leading zeros (Thanks @Niteshooter for the bug report): armel/uv-k1-k5v3-firmware-custom@cd7fcdb

• Fix VFO frequency input final digit handling: armel/uv-k1-k5v3-firmware-custom@3d4ffd7

• Bug fixes: Receiving the same channel in Dual Watch mode, disabling channel exclusion, changing the scan list, compilation error: armel/uv-k1-k5v3-firmware-custom@5b638e2
  No changes regarding channel exclusion and compilation errors

• UI improvements, backlight toggle in FM radio, code optimization: armel/uv-k1-k5v3-firmware-custom@793a448

• Added backlight fading, improved backlight control in spectrum: armel/uv-k1-k5v3-firmware-custom@5d88fda
  No backlight fading, just an improvement to the backlight in Spectrum

• Fix spectrum visualisation for edge cases: armel/uv-k1-k5v3-firmware-custom@2f01dd0

• Fix spectrum range: armel/uv-k1-k5v3-firmware-custom@1e33ff0

• App: clean up duplicate ARRAY_SIZE macros: armel/uv-k1-k5v3-firmware-custom@7189d09

• Minor cleanups and adjustments related to these changes: armel/uv-k1-k5v3-firmware-custom@e5ca226
  Only changes related to AirCopy

• Revert welcome.c and fix default keepAlive to 3 (PR armel#218): armel/uv-k1-k5v3-firmware-custom@e77e558

• Increase the keepAlive value, fix the CHIRP connection while maintaining the fix for the button getting stuck: armel/uv-k1-k5v3-firmware-custom@f4d8abd
  The only change is to the keepAlive value

• Minor code refactoring (24 B): armel/uv-k1-k5v3-firmware-custom@85dae05

• Improve SMeter Calibration: armel/uv-k1-k5v3-firmware-custom@4937d0b

• Fix for S-meter calculation, AirCopy - removed redundant code: armel/uv-k1-k5v3-firmware-custom@138e078

• Fix TXLock icon: armel/uv-k1-k5v3-firmware-custom@e555b48

• Add more scanlist: armel/uv-k1-k5v3-firmware-custom@dccdd37
  I just added “gScanStateDir != SCAN_OFF”

• Remove stars…: armel/uv-k1-k5v3-firmware-custom@6b4e575

• Overlap between Live DTMF and Unlock Keyboard (issue armel# 215): armel/uv-k1-k5v3-firmware-custom@5cb6bbd

• Displaying power bars during TX when using SetPwr: armel/uv-k1-k5v3-firmware-custom@f4a32b4

• Code optimization (32 B); Restore full VFO state on long press of EXIT: armel/uv-k1-k5v3-firmware-custom@aa69d69

• Improvements to the FM radio and side buttons: armel/uv-k1-k5v3-firmware-custom@bbbc553
  Just refactoring and fixing the crackling during beeps on the FM radio

• Code refactoring (64 B): armel/uv-k1-k5v3-firmware-custom@25b96be

• Code refactoring (136 B): armel/uv-k1-k5v3-firmware-custom@c5da503

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I carried over a lot of features from version V3, although I had to leave out things like backlight fading and button input from K5Viewer (the code was too large). As for the Basic version - check this out:

I'm looking forward to hearing your thoughts. I'm curious to see how these changes will work out.

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📺 Compiling Bandscope...
   text    data     bss     dec     hex filename
  60932      52    6676   67660   1084c f4hwn.bandscope
📻 Compiling Broadcast...
   text    data     bss     dec     hex filename
  60244      20    6304   66568   10408 f4hwn.broadcast
☘️ Compiling Basic...
   text    data     bss     dec     hex filename
  61372      52    3420   64844    fd4c f4hwn.basic
🚨 Compiling RescueOps...
   text    data     bss     dec     hex filename
  57728      20    6256   64004    fa04 f4hwn.rescueops
🎮 Compiling Game...
   text    data     bss     dec     hex filename
  61124      32    3240   64396    fb8c f4hwn.game