clang-tidy: const-qualification of parameters only has an effect in function definitions [readability-avoid-const-params-in-decls]

See https://clang.llvm.org/extra/clang-tidy/checks/readability-avoid-const-params-in-decls.html

See https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-using.html

Advantages:

- pure C++ for client code, no "<<< ... >>>"
- hence, clang-format can be used for source code formatting
- the HAVE_CUDA guards are not necessary anymore
- type of the kernel function can be added to exception messages
- easier debugging of kernel launch configurations

...and in a few other places to avoid compiler errors/warnings.

JK/fixes

See merge request !121

Does not work, disabled in CMakeLists.txt

Fixed copy-constructor in SparseMatrix

See merge request !120

It cannot be default, because the internal view would still point to the
original matrix.

Copyright headers for 2022 and forward

See merge request !118

Jakub Klinkovský authored Dec 25, 2021 and Jakub Klinkovský committed Jan 10, 2022

The old headers were hard to maintain, inconsistent and contained
useless information:

- file name (useless, prone to inconsistencies upon renaming)
- "description" (useless placeholder that was likely intended to be
  replaced by the user, not to be used literally)
- "begin" date for each file (prone to inconsistencies and copy-paste
  errors, the information can be found in git)
- "copyright" notice (inconsistent years)
- "email" (replaced with a project link in the new template)
- "Copyright Notice" referring to an obsolete file (tnl/Copyright) that
  does not exist anymore

The new template consists of three simple parts:

- copyright notice with updatable years related to the whole project
- project name and website URL
- SPDX license identifier

Note that the SPDX license identifier must be on a line that starts with
either "//" or "/*", so we can't use a block comment (/* ... */) for the
whole header. But using "//" for block comments is common too.

Jakub Klinkovský authored Dec 25, 2021 and Jakub Klinkovský committed Jan 10, 2022

Copyright headers in these files are useless, since they are not
distributed on the user's when they install TNL. They were also outdated
and inconsistent.

Documentation: fixed links between markdown files

See merge request !119

Doxygen changed their way of naming HTML files converted from Markdown
in the 1.9.3 release, but linking to other Markdown files is now
supported natively. No need for links to .html and the \page macro at
the top of each Markdown page.

Mesh followup

See merge request !117