Because of the Re-ARM card's pinout there is only one SPI connected to
the RepRap Discount Full Graphic LCD display.  The LCD responds to ANY
SCK transitions no matter if it's enable is inactive.  The result is
garbage (usually bars) on the LCD display whenever there is SD card
activity.

This code minimizes this by only accessing the SD card when changing
directory levels if :
SDCARD_SORT_ALPHA is enabled
SDSORT_USES_RAM is true
SDSORT_CACHE_NAMES is true

The code changes result in file names being pulled from the ALPHA SORT
memory array rather than the SD card.

The code also gives the file count and file index functions their own
variables.  When they shared a common variable the index function
sometimes resulted in the file count being short by 1.

=======================================================================

cardreader.cpp & pins_RAMPS_RE_ARM.h changes

Added another condition to cardreader.cpp to enable getting file names
only from RAM.

pins_RAMPS_RE_ARM.h :
Added comments about the SD card accesses and the LCD display
Combined all versions into this one.

Re-ARM has been tested.  AVR has not been tested.

1) moved all cpu specific items to files in the low level HAL directory
for that CPU (pinDebug_Re-ARM.h & pinsDebug_AVR_8_bit.h

2) added pinsDebug.h to the top level directory

3) modified HAL_pinsDebug.h to select the correct support file for the
selected CPU

4) Patched sanitycheck to stop throwing false errors.  A long term
solution will be done

5) misc changes & bug fixes
arduino.cpp - included macros.h to fix a missing definition
pinmap_re-arm.h - removed a duplicated line.
pinmapping.h - changed from "ENABLED" to "defined" to fix a compile
error

======================================================================

split SanityCheck up, improve pinsDebug system

======================================================================

switch to latest pins_RAMPS_RE_ARM.h