It should only be used by construction algorithms

public functions are already documented in their headers, no need to
repeat the comment at the definition site.

Define them in your own project if you must use them.

They were inconsistent with DEBUG_libfirm and unused

- Put things into logical groups
- Add cross references from node overview to API docu

They're pointless with the new switch representation introduced a while
ago.

Just changing offset of other entities is enough

memops are nodes that have memory inputs, you can generically query them
for their memory input. We can also get rid of get_fragile_op_mem in
favor of get_memop_mem.

(releases don't have firm_revision.h so we need to check for
HAVE_FIRM_REVISION_H define)

Moves code from ifg dot-file dumpers around and produces .vcg graphs
now (ycomp layout is way better than xdot)

(no changes in functionality)