Fix a compile error introduced in #98

With the introduction of the #if ENABLED(…)

reads better than

- `SD_DETECT_PIN` replaces `SDCARDDETECT`
- `SD_DETECT_INVERTED` replaces `SDCARDDETECTINVERTED`
- Revise the description of `SD_DETECT_INVERTED`
- Add a note about the override of `SD_DETECT_INVERTED` in
`Conditionals.h`

- Rename the pin so it can be tested with `PIN_EXISTS`
- Fix some incorrect tests for `SDCARDDETECT`

For consistency with other pins, allowing use of `PIN_EXISTS` macro.

Apply `ENABLED` / `DISABLED` macros to LCD-related files.

The compiler may be able to optimize if it knows an array won’t be
changing.

at least the lcd independent part from Marlin_main.cpp.

Also clean up some trailing spaces in a few other sources

by:
Moving HAS_LCD_BUZZ macro to Coditionals.h
Renaming HAS_LCD_BUZZ to HAS_BUZZER to make clear is has nothing to do with the lcd.
Removing the ULTRALCD condition.

Moving declaration of lcd_buzz() out of the ULTRA_LCD block in ultralcd.h
Moving definition of lcd_buzz() out of the ULTIPANEL block in ultralcd.cpp
Renaming lcd_buzz() to buzz() to make clear is has nothing to do with the lcd.

All buzzing code is now only dependent on the existence of a BEEPER-pin or the definition of a LCD_USE_I2C_BUZZER.

To do: Check the conditions for the BEEPER-pin in all pin-files.

Suggest we use the translated strings here. They use (except for
German) the phrasing “Move X” instead of just the axis letter, but they
should fit the available space. The “Extruder” string would be the
same, except it will be translated.

replace extruder_multiply with extruder_multiplier
like feedrate_multiplier or volumetric_multiplier

To avoid double definitions.
I prefer to read N for Number not for Nozzle.

to warrant watching is set or reset.

Make setTargetBed() in _lcd_preheat() dependant of TEMP_SENSOR_BED.
Use disable_all_heaters() in lcd_cooldown() and abort_on_endstop_hit.

Fixed a couple defines that were not changed or commented out.

Moved SDCARDDETECTINVERTED and SDSLOW to Conditionals.h.
Added U8GLIB_LM6059_AF to define display specific actions.
Added reminder to compile in u8glib

Rename of define to avoid confusion between the controller and the
display which had similar names.

Added support for new display type

- Also move audio feedback into the command
- Added shorthand for `lcd_buzz` availability

- Add “Level Bed” menu item for auto bed leveling
- Hide the option if homing has not been done yet
- Arrange the Prepare submenu more logically (?)
- Add documentation comments, some white-space
- Apply some coding standards here and there
- Move old encoder multiplier debug option to `ultralcd.cpp`

With these changes the output of `M503 S0` is all you need to restore
the EEPROM. Building on this it is straightforward to save and restore
the EEPROM state using the SD card or external GCode file.

- Added `M145` to set “heatup states” for the LCD menu
- Added `M420` to toggle Mesh Bed Leveling
- Added `M421` to set a single Mesh coordinate
- Extended `Config_PrintSettings` with added M codes
- Cleaned up some comments here and there

- Address issue raised in #1961

Centralised beep code to lcd_buzz().
From gcode_M300() and lcd_quick_feedback().

Enforced max. duration for M300 to 5 seconds.

Corrected description in 'Configuration.h'

LCD_FEEDBACK_FREQUENCY_HZ 0 gives now a silent delay of
LCD_FEEDBACK_FREQUENCY_DURATION_MS.

lcdDrawUpdate = 2 helped a lot!

- MENU_ITEM causes lcd_quick_feedback to be called, so only those calls
to `lcd_goto_menu` outside of the `MENU_ITEM` macro need to set the
`feedback` flag when calling `lcd_goto_menu`.

- Use `line_to_current` in place of `plan_buffer_line`