Add new WARNINGS var in Makefiles. Set to 1 when CHPL_DEVELOPER is defined.

WARNINGS will be used to enable and disable compiler warnings in
make/compiler/Makefile.* files. At present, those Makefiles enable and disable
warnings based on CHPL_DEVELOPER. There are situations where CHPL_DEVELOPER is
not set, but compiler warnings are wanted.
Use WARNINGS to enable warning flags in compiler specific makefiles.

Previously whether or not CHPL_DEVELOPER was defined determined if the warning
flags were added for C compiler. Instead, use the WARNINGS variable. This
allows a developers to build with compiler warnings enabled (e.g. when building
the runtime/) without the rest of the CHPL_DEVELOPER settings. Conversely, if
CHPL_DEVELOPER is set, a developer can disable C compiler warning flags by
setting WARNINGS=0 when calling make. The latter is not especially useful (or
recommended).
Copy .bash versions of setchplenv to .zsh version.
bash -> zsh
Merge branch 'master' of github.com:chapel-lang/chapel into add-warnings-opt
Update documentation for new WARNINGS variable in makefiles.
Cleanup output of .sh versions of setchplenv.

Use printf to print strings that should not have a new line char. I copied the
.bash versions and substitued `printf` for `echo -n`.
Add %s format argument to printfs
Update the string shootouts so that they will recognize the unused input value
sent to them through the Computer Language Benchmarks Game test suite.
Revert "Add %s format argument to printfs"

This reverts commit 0b7d971c49504e3b5ba024c6faa1079ecb4d26c4.
Revert "Cleanup output of .sh versions of setchplenv."

This reverts commit ba26a7031d1886155ebcdd8fd8e3a4de09bece37.
Revert "bash -> zsh"

This reverts commit 8abe3ce896c07d583927315bd8c9f1e7220e4103.
Revert "Copy .bash versions of setchplenv to .zsh version."

This reverts commit a0f8481be45796171b91f7b9425edefaf97a366a.
Add zsh to the list of shells that are bash-compatible.
Merge branch 'master' of github.com:chapel-lang/chapel into zsh-setchplenv
Add default format in integral_to_c_string_copy(), to keep Cray compiler happy.
Fix some remaining memory management problems after the c_string reimplementation.

The advertised interface to chpl_fs_cwd had not been updated to return a c_string_copy.
The low-level implementation returns an malloc'd string, so this is the right choice.

There was a coding error in getPath.  I had a call to chpl_free_c_string on the main value
after converting its type to use the "stealing" version of toString().  This violates the
coding convention associated with c_string_copies, and also (not coincidentally) resulted
in a premature free.

There was a long-standing error in qio_file_path_for_fd, where a call to qio_strdup was
left out for the LINUX case.  This would result in premature frees, but was only exercised
by the two test cases freadIntFailed and fwriteIntFailed.  Because MM error are
unpredictable, these test cases passed most of the time, but my change to the c_string
interface made them fail reliably.  The added call to qio_strdup() should fix these test
cases permanently.

I also added some comments regarding the MM responsibilities of callers of low-level
functions that return an allocated string.
Fix comment about nighly and CHPL_DEVELOPER.
Merge branch 'master' of github.com:chapel-lang/chapel into add-warnings-opt
Merge pull request #623 from hildeth/master

Add a future to describe the desired precedence of _defaultOf() over default constructor calls.