takes separate file handles for stdin, stdout, and stder and also allows for
the working directory to be specified.

Added support to "process launch" to a new option: --working-dir=PATH. We
can now set the working directory. If this is not set, it defaults to that
of the process that has LLDB loaded. Added the working directory to the
host LaunchInNewTerminal function to allows the current working directory 
to be set in processes that are spawned in their own terminal. Also hooked this
up to the lldb_private::Process and all mac plug-ins. The linux plug-in had its
API changed, but nothing is making use of it yet. Modfied "debugserver" and
"darwin-debug" to also handle the current working directory options and modified
the code in LLDB that spawns these tools to pass the info along.

Fixed ProcessGDBRemote to properly pass along all file handles for stdin, stdout
and stderr. 

After clearing the default values for the stdin/out/err file handles for
process to be NULL, we had a crasher in UserSettingsController::UpdateStringVariable
which is now fixed. Also fixed the setting of boolean values to be able to
be set as "true", "yes", "on", "1" for true (case insensitive) and "false", "no",
"off", or "0" for false.

Fixed debugserver to properly handle files for STDIN, STDOUT and STDERR that are not
already opened. Previous to this fix debugserver would only correctly open and dupe
file handles for the slave side of a pseudo terminal. It now correctly handles
getting STDIN for the inferior from a file, and spitting STDOUT and STDERR out to
files. Also made sure the file handles were correctly opened with the NOCTTY flag
for terminals.

llvm-svn: 124060