Fixed a little slip with nasty consequences
Improved handling of symlinks
Changed test for irrelevant islands from count=0 to count<=1
WIP implementation of sieve-driven shred scheduler.
WIP
initial implementation (compiles with warnings)
More-or-less working version, needs optimising and lots of tidy up
Simplified queue order
Bashed it more-or-less into working order.
Benchmarks look ok on limited testing.
Merge branch 'develop' of https://github.com/sahib/rmlint.git into sieve_format_merge

Conflicts:
	src/cmdline.c
	src/file.c
	src/file.h
	src/preprocess.c
	src/session.c
	src/shredder.c
	src/traverse.c
Minor edits post-merge to get working again
Merge branch 'develop' of https://github.com/sahib/rmlint.git into sieve_format_merge
fixed minor compiler warning
documentation
corrected double-call of rm_shred_run
Cleaned up helgrind warnings (some left, but only false positives)
only minor cleanup and added some remarks
Some assert and style issues less
Removed some outcommented code (I guess 1 readthread per device is okay)
Removed phys_offset from RmFile - calculated on the fly now