This is a major Makefile refactoring:
differentiate between:
- source files in $(srcdir)
- generated files in $(top_builddir)/gen
- object files in $(top_builddir)/$(variant)/ aka $(builddir)
- documentation in $(top_builddir)/doc

Types need not be in their final form after the new_entity so there is no
need to have _d variants like we have with all the graph nodes. You can easily
use set_entity_dbg_info() after construction.

Entities need not be in their final form after the new_entity call, so
there is no need to have _d variants like we have with all the graph
nodes. You can easily use set_entity_dbg_info() after construction.

Directly reading tp->align breaks (at least) for array types.

It is not usefull for optimization in most languages:
- In C/C++ you can't really change the value of enum constants as casting
  from/to integer has to produce the expected results.
- In Java (and other OO languages) enum members are objects so the
  libfirm enumeration type can't be used there anyway

As they were just a single flag the name should reflect that. I did not
change arch_irn_flags_none, as that is not about a single flag.

- fix: not just aggregate parameters need special handling but also
  aggregate return types.
- don't just look at the called function but also on the call type.

This is a type which is aggregated from multiple primtive/simple
elements. In libfirm such a type cannot be represented as a mode.

few typo fix

This allows users - such as Special Instruction creation for
reconfigurable microarchitectures - to override the backend's
predicate.

This removes all predecessors from Syncs which are reachable through a path
beginning at another predecessor.

Like a Store, a non-volatile CopyB whose destination is never read can be
removed.

If a Load reads from a location written to by a previous CopyB, we can use the
equivalent memory location in the CopyB's source buffer for further
optimizations (e.g. Load-after-Store).

In addition, if said CopyB source buffer is constant (e.g. an initializer),
we may directly replace the Load's pointer value with the equivalent memory
location in the initializer.