v1.27
- FFT (channel A or Channel B) and Spectrograms  (channel A or Channel B) now accessible in the Channel 4 menu
- Merged all contributions from Wildcat:
	INTERFACE:
		- Variable repeat rate for toggles, slow for menus, fast for verniers, etc.
		- Main Menu will stop at left (CH-A), and at right on Time Vernier or Volume adj, will not "go around".
		- Program will attempt to set triggering to relevant channel, if shutting off a channel with trigg set,
  			will move trigger source to last selected ch.
		- Will not time out into standby if USB power plugged in.
		- "SCAN" mode renamed "TrOFF". Trigger levels/vernier do not show in this mode.
		- "NorCL" (Normal-Clear) mode added (simulates regular CRT type scope, clears display if no trigger)
		- Single shot trigg mode automatically goes into full size buffer mode.
		- Digital channels meter default displays changed to show only relevant meters (no volt meters)
		- Trigg verniers disabled for digital channels (preset at 1/2)
		- X_Y-A and X_Y-S removed, now only X_Y. Mode is triggered in AUTO mode to allow meters to work correctly. (Move trigg
  			source to unused ch to disable triggering if desired).
	TRIGGERING:
		- Re-sequencing of triggering functions to allow proper time for reset to bring up start flag before attempting to read
  			FIFO, allows analog channels to trigger properly on slow/random signals at fastest timebases.
		- Fixed a problem in the mid-range time bases where display would freeze or trigger very sporadically
		- Implementation of proper triggering in single screen buffer mode.
		- Various functions optimizing triggering for different timebases, triggering modes, etc.
		- "SCAN" mode (now renamed "TrOFF") optimized with different routines for fast and slow time bases.
		- Single screen buffer mode now resets immediately after right edge of screen, also is available at all time bases.
		- Auto trigger fix to eliminate condition in some cases where device could not trigger because trigg level was too far
  			away from wave and auto function could not find wave because device was not triggering.
	CALIBRATION:
		- Gain calibration now modifies signal in relation to signal zero point, rather than screen bottom. Prevents
  			interfering with offset calibration and Y positioning.
		- Signed variables now used to allow values at bottom of screen, which can be pushed up by offset calibration, and
  			then be below zero, to be read properly.
		- ADC operating point shifted away from non-linearity at the bottom of screen. Allows calibration routine to
  			work more accurately.
		- Fix for an error in FPGA where the 2 least significant bits of CH-B are swapped.
		- Fix for an error in saving parameters to disk where CH-B offset compensation could be corrupted if CH-A's value was
  			negative.
		- Signal gain calibration now switchable ON/OFF (Screen only, does not affect meters. Improves wave quality by removing
  			correction "steps", if present).
	FILES:
		- Fixed BMP header. Header was missing a row of digits causing improper file and image size to be listed.
		- Added several additional parameters to be saved in "save config". (Config file still compatible with previous versions)
	METERS:
		- Values now corrected by calibration in reference to signal zero point, rather than screen bottom. Prevents offsets and
  			Y positioning from affecting accuracy.
		- Time measurements in process completely re-written, eliminating the inclusion of partial waves before triggering. While
  			this only affected accuracy slightly in full frame buffer mode, it introduced major inaccuracies in single screen buffer
  			mode where at times only a few waveforms are considered in the measurements.
		- Frequency meter fixed so it works past ~2Mhz. This worked OK in original program, but had wrong suffix. Subsequent fix for
  			improper readout caused meter to malfunction past around 2Mhz.
		- Fixed Time and Voltage Vernier meter readouts so they display properly at very large and very small time/voltage settings.
	GENERATOR:
		- Shifting of amplitude variation from signal's zero point rather than screen bottom, eliminates distortion at lower levels
  			where bottom of wave is clipped. Note that this results in an unchanging DC offset as level is varied... (use AC coupling
  			to display properly)
		- Changed division ratios so proper frequency is produced/displayed without needing a special SYS version (should work OK with
  			it as well) Only issue with this is the innability to produce 20Khz (produces 25Khz instead) Readout shows correct value.
	DISPLAY:
		- Improved linearity from ADC operating point shift. (Eliminates compression of wave at bottom of screen).
		- Bit swap correction on CH-B improves trace quality.
		- Elimination of noise at beginning and end of trace on some ranges.
		- Alignment of Digital channels with Analogs. Note that digital channels trailing at very fast timebases is caused by
  			delay introduced in Digital channel input stage. There is no way to fix this at the software level, needs to be fixed
  			in hardware.  This same input stage configuration also introduces instabilities when triggering from the digital CHs at
  			fast time bases.
		- Re-aligned trigger point with trigger vernier
		- Fixed "time shift" at fastest timebases when changing time/div while on hold.

Signed-off-by: Pedro Simoes <pmos69@hotmail.com>