pump version number after meaningful merges

[derNarr]

Hi all,

the last merge, which introduces version of vtlTractToTube should increase the version from 2.4.2 to 2.5.0, if you want to follow some semantic versioning practices.

At least I would expect to have a different version string for each merge that changes the code base, as this can drastically help to debug user problems with the VTL backend.

But this is only a suggestion :-)

Best,

Tino