fix c fun prototype mismatch; fix sac code fun type
Use the lpel target in sac2c interface code
gigo1 example; clean makefile for it

a bug in sac2c, presumably in ref cnting
./gigo-lpel <input2.xml
sac4snet interface plugin: specify the default mapping of SAC worker tasks by environment variables
sac4snet.txt: document the metadata used in SAC plugin
sac/tests/gigo1: overload funcstions for different array shapes
examples/SAC/gigo1: update the example to demonstrate the use of the dynamic default placement
sac4snet.txt: installation instructions
sac4snet: create a small execution realm (a single-bee hive) for SAC Print/Scan calls

This silences the SAC warnings about a missing hive.
sac4snet: remove a debug print
sac4snet.txt: make it a proper RestructuredText
Fixed the execution realm support for SAC.
Assumes exerealm_create does not need to run in the same thread as the box code.
(merge from Merijn Aug 24 2012)