Document this week's experiments.
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
changed include statements in scc distrib files
fix bug of repeating message IDs
 - reason: SNetRecCopy copy a data record without creat a new
   record/message ID. This function is called by split and sync
 - in syncro.c: clean up the code a bit
Merge branch 'master' of git://github.com/snetdev/snet-rts into main_branch
Clean up the code in syncro.c
Conflicts:
	src/runtime/stream/entity/syncro.c
fix conflict in syncro.c
  + clean up code which calls monitoring user data (message information)
Merge pull request #29 from knz/experiments-201208

Document this week's experiments.
Merge pull request #25 from jsyk/pullme1

Dynamic default placement of SAC bees via environment variables
Merge pull request #26 from ra-one/master

Modified some included statement causing error when compiling for SCC
Merge pull request #28 from nguyenvuthiennga/main_branch

fix the bug of repeating message IDs
fix garbage collector:
 - implemenation: see the gc docs
 - only one macro to enable the garbarge collector (in include/thread.h)
fix GC bug
  + implementation: see docs
  + use only one macro to enable the gc (in include/threading.h)
accidentally remove some code while fixing gc bug --> add back now