Let the user choose between gcc and clang via NRE_CC.
Provide operator new for clang.
Don't use a flexible array in Consumer.

Clang complained and we don't need it.
Added memchr because clang generates a call to it.
Call constructors of clang (slightly different from gcc).
OStream::Format has to be public.
Compile libseoul with clang.
Fixed warnings detected by clang.
Added packet-producer and consumer including unit-tests.
Fixed error for non-existing services.
Added network support.

In detail:
- now we have a network service with a NE2K driver.
- the vmmanager has been extended to give out MAC addresses in
  order to assign a different one to each VM.
- Tinycore Linux has been added for network tests.
- seoul builds the intel82576vf model now (both on x86_32 and
  x86_64)
Fixed a bug in tools/linuxextract.sh.
Show the application name in the log, not the session-id.
Fixed a bug in OStream.

The padding wasn't correct if a precision was specified for a
string.