to make it better findable.

- Make thermal protection for all hotends and/or bed into simple
switches
- Now enable `WATCH_TEMP_PERIOD` when `THERMAL_PROTECTION_HOTENDS` is
enabled
- Move detailed thermal parameters to `Configuration_adv.h`
- Add sanity checks to warn about old configurations
- Change `WATCH_TEMP_PERIOD` to seconds instead of milliseconds

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

- Change some `previous_` time vars to `next_` so an add only happens
at intervals
- Fix `HEATER_0_USES_MAX6675` polling too frequently, or not at all

This commit checks whether or not HEATER_0 is in use, and if not, skips
the MIN / MAX temperature checks.

It wouldn't compile because of this line in temperature.cpp it turns out
it was just a stray ( that didn't line up with the previous lines so I
just made it in line with the rest and it compiled fine.

- Add comments documenting `thermal_runaway_protection`
- Add an enum for the thermal runaway states
- Add macros for temperature helper functions
- Fix a glitch with the z probe sled in homeaxis

and use them in temperuture.h

Flattened the if structure - the preprocessor is doing the work - not the Arduino. Arduino.

replaced GE0 with th matching GEX in the second row.
added some ()

- Make the default LCD click sound more pleasant
- Fix warnings about bed temperature runaway

cardreader.cpp needs temperature.h for autotempShutdown() when
AUTOTEMP is defined but warns about unused variables.
Unpublished variables by putting them in to temperature.cpp.

- Patched up for most included configurations

- Fix a bug reading `code_value` for `M503 Sn`
- Hide and remove unused variables

make it unconditional
remove all definitions in the 'Configuration.h's
remove form 'Conditionals.h'

to make the temperature-code work again with Arduino 1.0.6.

Sorry could not make an extra block on base level.

- Remove test of raw temp for thermistor 0 when using MAX6675
- Longer `raw_temp_value` array for `TEMP_SENSOR_1_AS_REDUNDANT`

- Get rid of unused temp states in the ISR, resulting in more frequent
temperature reading with fewer sensors
- Shrink code slightly in min/max testing