SD Sort and Buffer

SDCARD_SORT_ALPHA: Alphabetical (case-insensitive) directory sorting for SD cards uses pre-reading to build a sorted list of indexes, 1 byte per entry. Includes an option for folders to sort first, last, or not at all.

Three variants are included:

- Slow but efficient, reads names from SD throughout sorting. (SORT_USES_RAM = false)
- Faster but expensive, gets the names, builds the index, then frees names. (SORT_USES_RAM = true)
- Most expensive. As above, but keeps the long (and short!) names in SRAM to optimize SD navigation speed. Frees the names when printing begins. (SORT_USES_MORE_RAM = true)