Sort include alphabetically and make them in order:
Main header
system headers
library headers
local headers
While reordering, change a include of endian.h to our sparse-endian.h
which is more reliant to toolchain changes.
The PSTR is already define as a NOP for all supported platforms. It's
only needed for AVR so here we remove all the uses throughout the
codebase.
This was automated with a simple python script so it also converts
places which spans to multiple lines, removing the matching parentheses.
AVR-specific places were not changed.