* Add support to specify global build defines and options

A script manages the use of a file with a unique name, like
`SketchName.ino.globals.h`, in the Sketch source directory to provide compiler
command-line options (build options) and sketch global defines. The build
option data is encapsulated in a unique "C" comment block and extracted into
the build tree during prebuild.

* Applied os.path.normpath() liberally to input arguments. Fixes windows file path issue.
Improved helpful message for adding embedded build options.

* doubleup '\'

* Added context help for build option support

* expunged sketchbook global
added workaround for aggressive caching

* inital pass at searching for and reading preferences.txt

* Correct Windows path for preferences.txt
Added portable path for preferences.txt
Expanded file timestamp granularity
Improved error message printing for Arduino IDE 2.0 RC4

* Improved portable path and various Windows paths to preferences.txt

* Add cleanup logic and identify 1st run after IDE restart

* text corrections

* Create mkbuildoptglobals.py

When global header file does not exist, this print makes it easier for user to create the header file by providing its name and documentation pointer.

* build.opt heads up to user

Compiler command line changes from build.opt are shown to user

* Updated text

* oops

* Expanded comment and made print help consistent

* Improve handling stderr/stdout with "no verbose output"
Grouped helpful info to print at the end.
Added missing return value.

* Correct timestamp on CommonHFile.h
More improvements to printing
Updated docs.

* Added command-line parser

Support hints for compiler.cache_core. For use when Arduino IDE uses
command-line options that override compiler.cache_core.

Removed overuse of ()

Improve FAQ entry

* Fix script failure under windows

Rely on argpaser for checking that all arguments are present.
Removed redundant argument check in main().

Added '--debug' option and print_dbg method.

Rethink failures on overrides. Remove well know path fallbacks,
error exit when override file is missing.

In well-known path search for preferences.txt, do not assume true.
Make failure to find an error exit event.

When Windows has two preferences.txt files and they have different
values for caching and globals.h is used, error exit. It is not
possible to know from the script which is being used.

* Use quotes on build.opt

Update comment
Include the @ within the expantion string use quotes around file name.
Update doc example to remind and use quotes.

* Update CI for build option and global support

Added "mkbuildoptglobals.extra_flags=--cache_core" to platform.loca.txt
Update "-ide-version=10802" this version number indicates aggressive caching support
Added example to test global .h support

* Add debug prints
Added --debug to CI - this needs to be removed later
Tweaks to touch...

* Give each build VM a unique build.tmp space

* Corrected style on example
temp CI changes
debug crud
Added --ci switch

* Removed CI debug crud

run_CI_locall.sh works fine locally. Hosted Multi-VM CI fails
to work with 'aggressive caching' workaround method.

Add #if defined(CORE_MOCK) to failing example.

* Try HOST_MOCK

* CI adjustments

mkbuildoptglobals.py is optimized around the Arduino IDE 1.x
behaviour. One way the CI differs from the Arduino IDE is in the
handling of core and caching core. With the Arduino IDE, each sketch
has a private copy of core and contributes to a core cache. With the
CI, there is one shared copy of core for all sketches. When global
options are used, the shared copy of core and cache are removed before
and after the build.

* Doc update