Release v4.13.1-patched-snapshot_2020-09-18

QtCreator 4.13.1 + patches:

• display snapshot version in about dialog
• properly indented line comments
• no jump to task list after build errors
• use patched qbs for Windows build
• use "c++2a" (gcc/clang) / "c++latest" (msvc) from qbs for clang code model

Qbs 1.17 + patches:

• cxxLanguageVersion: "c++2a" is allowed. Note: It will trigger "c++latest" for msvc
• visual studio (msbuild) project generation is more usable (still opinionated)