Issues fixed

Issue 512: Backport PR 509 “Add PIE for some tools” to all rliv branches

For more details, see https://github.com/thelfer/tfel/issues/512.

Issue 487: [tfel-config] remove reference to svn revision

For more details, see https://github.com/thelfer/tfel/issues/487.

Issue 466: Fix build with gcc 13

For more details, see https://github.com/thelfer/tfel/issues/466.

Issue 465: Thermal conductivity SI unit

For more details, see https://github.com/thelfer/tfel/issues/465.

Issue 460: [tfel-config] allow to modify the compiler flag associated with the C++ standard

For more details, see https://github.com/thelfer/tfel/issues/460.

Issue 459: [mtest] correct the documentation of @OutputFrequence

For more details, see https://github.com/thelfer/tfel/issues/459.