Add -E support in executables, for use by launchers in forwarding the
environment to the user program processes when the underlying system
launcher can't do so.  The changes are:

runtime/src/arg.c
  Add -E option parsing and environment variable setting.

doc/release/README.executing
  Document the new option.

test/execflags/ferguson/help2.good
test/execflags/shannon/configs/help/basehelp.txt
test/execflags/shannon/help.good
  Update the expected "-h" output.

test/execflags/gbt/dash-E-1-opt.chpl
test/execflags/gbt/dash-E-1-opt.execopts
test/execflags/gbt/dash-E-1-opt.good
test/execflags/gbt/dash-E-1-opt.skipif
test/execflags/gbt/dash-E-2-opts.chpl
test/execflags/gbt/dash-E-2-opts.execopts
test/execflags/gbt/dash-E-2-opts.good
test/execflags/gbt/dash-E-2-opts.skipif
  New unit tests.
Merge branch 'master' of github.com:chapel-lang/chapel into dash-E
Fix bug in cache
Stop adding duplicate fences in waitFor

Fences I added here are also added by the compiler
when --cache-remote is enabled, but they don't do
anything if --cache-remote is not enabled, so they
don't need to be explicitly included here.
Relax task counting fences, add barrier fence

The task counting atomics don't need to imply fences
as these are handled elsewhere and we're really just
updating a counter.

For the barrier here, it's waiting on (not atomic)
local memory to change from a remote locale's put - which
is not legit according to the memory model... add
a fence (but I'd like to see a better barrier).
Initial support for specifying stdin file in execopts
Using execopts stdin file for knucleotide
Using execopts stdin file for reverse-complement
Changes through Tuesday mid-day.
Merge branch 'master' of github.com:chapel-lang/chapel into REG-TRI
Wednesday updates.
Today's changes.
Ready for unit testing.
Merge pull request #51 from ronawho/master

Enable "--enable-condwait-queue" for chap03/04 qthreads performance testing
Fix problems with NetworkAtomics from r23794

r22107 fixed some wrong return types for Atomics.chpl,
and r23435 and r23472 fixed that for NetworkAtomics.chpl,
but my patch r23794 inadverdently undid some of these changes.

Here I put the changes back. Some other notes:
 - I added explicit return types to read and peek methods.
   That seemed to make it fit in better but the corresponding
   change would also need to be done in Atomics.chpl for peek.

 - I did not add :void return types to e.g. add or sub methods,
   but somebody could do that if it's important to match the style
   used in Atomics.chpl

 - I fixed peek and poke for ratomicflag to work with bool instead
   of int(64).

Tested with 'make check'.
Merge remote-tracking branch 'upstream/master' into cache_fixes
Updates to GitCheatSheet with outline
Fix order
Fix warnings about void* pointer arithmetic
Fix wording