Update command-line options, script variables, and documentation to use
the term "group" instead of "track". The old terms are still available
for now, but they are now undocumented.

This makes our terminology more consistent with CDash. The goal of this
change is to make it more clear to our users how CTest and CDash interact
with each other.

* Move USE_MYMATH from configured header to target_compile_definitions

* Remove comments from CTestConfig.cmake
* Update directions

* Update directions

* Print message when using the table
* Remove duplicated comment
* Remove HAVE_LOG and HAVE_EXP checks, use generated table instead

* Updated output message
* Use 'target_compile_definitions' for HAVE_LOG and HAVE_EXP

Previously, the change from using TutorialConfig.h to
target_compile_definitions happened without explanation as part of Step 8.

* Clarify directions

* Move `option(USE_MYMATH...` to the same location in all CMakeLists files

* Fix typo in #include
* Remove CMakeLists file that users should create
* Clarify which files users are expected to create
* Highlight the importance of configuring TutorialConfig.h.in after
  the MY_MATH option has been set

* Update minimum required version to 3.10
* Use VERSION argument to project command rather than separate variables
* Replace `endif(USE_MYMATH)` with  more modern `endif()`
* Simplify the call to 'configure_file()'
* Add comments to tutorial.cxx to use as anchors in documentation
* Remove CMakeLists and TutorialConfig.h.in files that users should
  create. Consequently, remove Step1 from CMake tests.

We removed installation of `Help/index.rst` in commit d2fde948 (Help:
Add infrastructure for guide-level documentation, 2019-05-30), but the
file is required for `--help-full` to work.  Restore installation of the
file and update it to avoid referencing the `Help/guide` directory in
its toctree during processing by `cmRST`.

Inspired-by: Rainer Orth
Fixes: #19456

This enables the use of MSVC and Swift on Windows in a single project.
MSVC uses no flag to indicate linked libraries while Swift uses `-l`.
Add support for a language specific link library flag which takes
precedence over the global `CMAKE_LINK_LIBRARY_FLAG` which preserves
compatibility with earlier releases.

The NDK build system now uses only a single toolchain in

    <ndk>/toolchains/llvm/prebuilt/<host>

Its compilers are always `bin/{clang,clang++}` and its binutils are
always `bin/<triple>-*`.  It is a standalone toolchain:

* The Anrdoid API level is specified at the end of `--target=`.
* The standard library may be specified via `-stdlib=`.
* No need to pass system includes or libraries explicitly.
* No need to pass `--sysroot` or `-gcc-toolchain`.

Teach CMake to recognize NDK versions that have a unified
toolchain with its own sysroot and use the above approach.

Fixes: #18739

Revert the change from commit 7b354baa (CMakeVersion: Set
CMake_VERSION_RC to 0 even in non-rc versions, 2019-07-25) and instead
define a `0` value in `CMake_VERSION_RC` to mean `-rc0`.  This
distinguishes release branch versions prior to the first release
candidate from the first release candidate itself.  It also makes room
for a dedicated "CMake $major.$minor.0-rc1" release commit for `-rc1` as
we have for later release candidates and final releases.

The logic that uses this value already ignores any "false" value, so `0`
is just as good as not being set at all.  Using `0` for this role makes
the version components look more symmetric and reduces the number of
edits needed when creating releases.

Use compiler flags and standard levels as the compelling argument
for using generator expressions and interface libraries

Fixes #15592

Revert the changes from commit a2a90f41 (Tests: require C++14 for the
Tutorial, 2019-03-21, v3.15.0-rc1~41^2~2) for the content in its new
home.  In commit d50b31be (Clang: For MSVC ABI do not use modes older
than C++14, 2019-07-23) we fixed the C++ standard selection for GNU-like
Clang with the MSVC ABI so the test code itself no longer needs to do
it.  In particular, changing the tests in this way broke the tutorial's
narrative.

The singular name `CPACK_INSTALL_SCRIPT` has existed but was not linked
from the CPack documentation.  Also, it supported multiple values and
should have had a plural name.  Add a plural-named alternative now.
If both `CPACK_INSTALL_SCRIPTS` and `CPACK_INSTALL_SCRIPT` are set then
ignore the latter with a warning.
Signed-off-by: Alex Turbov <i.zaufi@gmail.com>

This is preferred over using `make install` as it allows for control
over the install location, configuration, and component.

By default `CMAKE_MSVC_RUNTIME_LIBRARY` is not set.  Document the
default runtime library selection in that case.  We already test it.

Fixes: #19465

Query the number of logical CPUs available to enable parallel
compilation for Swift.