This MR includes some cleaning up of the common Herwig7_i repository on the master branch (rel22).
Two separate LHEF configuration files (for Herwig versions 7.1.x and 7.2.x respectively) are merged into a single file that fetches the Herwig version from the $HERWIG7VER environment variable.
The EvtGen file is renamed to avoid confusion for which Herwig version it is suitable. (It is suitable for both 7.1.x and 7.2.x, but the previous name suggested otherwise.)
Tagging @dhirsch