When one hit "Stop Print" option in LCD menu, the command buffer was not
cleared. The printer keep moving until the buffer has been emptied.
Actually I could not clear the command buffer as well.. I don't know
why, it doesnt work as expected.
I need to implement a routine inside Stepper ISR to handle such
situation.

- Apply standards to cardreader.*
- Fix minor issues with cardreader.cpp
- Apply standards to some other stale regions

Introduced lcd_strlen() and lcd_strlen_P().
Replaced the old functions where necessary.
Reworked language_ru.h.

Speeded up test for zero length string in cardreader.cpp

Replace instances of the number 13 with FILENAME_LENGTH where
appropriate.

Replace instances of the number 13 with FILENAME_LENGTH where
appropriate.

For the MORE_RAM option we need to buffer both the short and long
names, even though long names are sometimes redundant. Worst case, all
the names are max length. We can save some RAM by not storing these. We
could save more RAM by only storing the visible part of the long name.

With this option, always keeps the dir in RAM, doubling as a cache for
getfilename. A board with only 8K of SRAM is cutting it very close.

First iteration of alphabetical sorting for SD cards, both
slow+efficient and fast+rammy. Option for folders to sort first, last,
or not at all.

For the MORE_RAM option we need to buffer both the short and long
names, even though long names are sometimes redundant. Worst case, all
the names are max length. We can save some RAM by not storing these. We
could save more RAM by only storing the visible part of the long name.

With this option, always keeps the dir in RAM, doubling as a cache for
getfilename. A board with only 8K of SRAM is cutting it very close.

First iteration of alphabetical sorting for SD cards, both
slow+efficient and fast+rammy. Option for folders to sort first, last,
or not at all.

For the MORE_RAM option we need to buffer both the short and long
names, even though long names are sometimes redundant. Worst case, all
the names are max length. We can save some RAM by not storing these. We
could save more RAM by only storing the visible part of the long name.

# The first commit's message is:
SD Card Alpha Sorting

First iteration of alphabetical sorting for SD cards, both
slow+efficient and fast+rammy. Option for folders to sort first, last,
or not at all.

# This is the 2nd commit message:

Expand on More RAM concept, address minor bugs

# This is the 3rd commit message:

Improvements, more SORT_USES_MORE_RAM

With this option, always keeps the dir in RAM, doubling as a cache for
getfilename. A board with only 8K of SRAM is cutting it very close.

# This is the 4th commit message:

Completed SORT_USES_MORE_RAM implementation

For the MORE_RAM option we need to buffer both the short and long
names, even though long names are sometimes redundant. Worst case, all
the names are max length. We can save some RAM by not storing these. We
could save more RAM by only storing the visible part of the long name.

For the MORE_RAM option we need to buffer both the short and long
names, even though long names are sometimes redundant. Worst case, all
the names are max length. We can save some RAM by not storing these. We
could save more RAM by only storing the visible part of the long name.

With this option, always keeps the dir in RAM, doubling as a cache for
getfilename. A board with only 8K of SRAM is cutting it very close.

First iteration of alphabetical sorting for SD cards, both
slow+efficient and fast+rammy. Option for folders to sort first, last,
or not at all.

For the MORE_RAM option we need to buffer both the short and long
names, even though long names are sometimes redundant. Worst case, all
the names are max length. We can save some RAM by not storing these. We
could save more RAM by only storing the visible part of the long name.

With this option, always keeps the dir in RAM, doubling as a cache for
getfilename. A board with only 8K of SRAM is cutting it very close.

First iteration of alphabetical sorting for SD cards, both
slow+efficient and fast+rammy. Option for folders to sort first, last,
or not at all.

This leads to the command not being acknowledged properly
by the firmware, leading to consecutive issues in host software
waiting for an acknowledgement.

Preference is for Controller SD slot before LCD Panel slot when both are occupied.

If a print is stopped, it would be nice in the future to write a file with the printer state, the filename of the print, and the position within the print.
this file could be read, to continue a previously stopped print.
not finished yet.

by overloading M32 it is now possible to execute gcode files from other gcode files, with a fixed recursion level.
This can be used e.g. for having a real start.g and end.g somewhere on the sd card, which are then called from the normal print file.
Another usecase would be to have macro-files for nozzle-change and layerchange.
I have not tested the speedwise performance. The testing was done with pronterface.

syntax:
normal call from sd card will open the new file and continue executing there.
M32 !/path/filename#
this however will call the new file and return to the caller file.
M32 P !/path/filename#
with the optional "S<position>" the  file starting position can be set.
this is for continuing prints from a previous location.

Untested