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
Initial support for specifying stdin file in execopts
Using execopts stdin file for knucleotide
Using execopts stdin file for reverse-complement
Ready for unit testing.
Add local blocks to the BlockStmts walked during return path checking

The statements in a local block should be walked in isDefinedAllPaths in the
same way as for plain BlockStmts and do-while BlockStmts.  This gets rid of the
warning in users/ferguson/local-return.chpl, so remove that .future and .bad.
Merge branch 'master' of github.com:chapel-lang/chapel into dash-E
Snapshot:
- update parseArgs() to know whether it's the launcher or user
  executable and whether it's parsing -E options or others
- call parseArgs() early to do -E options in main, later for the rest
- call parseArgs() in the launcher
- Merge the two dash-E tests into one, with two .execopts entries.
Merge branch 'master' into stdin-in-execopts
Produce an error if a .stdin file exists and one is specified in execopts
Add chpl_free_c_string() and use it to clean up leaked c_strings in
string and IO code.
Merge branch 'master' of github.com:chapel-lang/chapel into c_string-leaks
Merge branch 'master' of github.com:daviditen/chapel into localReturn

Conflicts:
	test/users/ferguson/local-return.bad
rebasing to get rid of whatever happened on the old one...
adding changes based upon review comments
Resolves all but 3 of compile-time failures.
Removed assertion that the PRIM_INIT clause in preFold is never reached.
Fix a few bugs with PRIM_TYPE_INIT.

resolveCall() must apply default generic type resolution to the PRIM_TYPE_INIT primitive.

CallExpr::prettyPrint() had to be updated to recognize PRIM_TYPE_INIT as an "unusual"
case.
Merge pull request #81 from daviditen/localReturn

Add local blocks to the BlockStmts walked during return path checking

The statements in a local block should be walked in isDefinedAllPaths in the
same way as for plain BlockStmts and do-while BlockStmts. This gets rid of the
warning in users/ferguson/local-return.chpl, so remove that .future and .bad.