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
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.
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.
Adding my changes to the minimalModules test. With default initialization,
these tests would not work otherwise.
This adds the compiler generation of the defaultOf for externs, and removes
the previous handling of externs from functionResolution.
Adds compiler functionality for a module-defined _defaultOf function for each
type.

Summary of changes:
buildDefaultFunctions - generates the _defaultOf function for record types.
  Inserts accesses to the type's type and param fields such that these can be
  grabbed in function resolution and sent to the correct constructor.  Default
  initializes the remaining fields unless the constructor has a default
  expression in its function header.

callDestructors - In changeRetToArgAndClone, instead of only alterring the first
  use of the old return symbol, alter all the uses to copy the updated value of
  the return parameter into the old return symbol before actions happen to its
  remaining uses.

functionResolution - Replace the varying actions to types depending on flags,
  defaultValues, etc, with calls to the _defaultOf method of that type (which
  should do the varying actions for it).  Except distributions, which require
  a little more functionality to utilize a _defaultOf function.  Distributions
  can't generate a _defaultOf method in the module code because our construction
  via type aliases (new <alias>()) does not work when the alias was not created
  in a straight-forward way, and buildDefaultFunctions can't generate a
  _defaultOf method because it doesn't have enough type information to insert
  the proper calls.
Today's updates.
Adds the _defaultOf generation for tuples.

Not all type information or substitutions for tuples are known by the time
buildDefaultFunctions comes around, but it needs to have a _defaultOf method
around to instantiate by the time functionResolution rolls in for generic
instantiation.  So create a stub in the former and fill in the body in the
latter.
Add the _defaultOf function for booleans
Add _defaultOf for inits, reals, and imags.
Add _defaultOf method for enums.
_defaultOf method for strings and c_strings