fix preprocessor -E output after recent compilation loop rewrites
add __XXX_C(c) preproc defines
some cleanups
add some notes about the AST printer
adapt to libfirm new_d_entity,new_d_type removal
make sure comments for exported status functions are in the headers
use gcc -MP instead of match-all %.h rule in Makefile
adapt to libfirm Makefile changes
report errors for bad -O opts, interpret -Os as -O2
make sure to (p)close the input on some external preprocessor calls
fix returncode for --help