Revive shower

[Juergen Reuter]

We should refactor the shower. This is the content of the old shower TODO file from 2014: !!!!!! TODO

• PYINIT only once? lhapdf_init only once?
• interface for hadronization

-> writing back: Kf not known for hadrons by W-model

• proper treatment of beam-remnants

=> if s gets kicked out of hadron, PYTHIA generates meson (sbar + u or d)

• observables (thrust) etc.

-> so far no global observables present?

!!!!!! partly done

• set PDFset => ticket "Shower takes only current PDF set" ?

!!!!!!! TODO but probably useless

• add support for showering of squarks and gluinos
• find memory leak <-> many particles(?)

!!!!!!! done

• implement switch to treat all partons emitted in spacelike shower as onshell -> fastisr
• pt_orderd => prt%typ=0 found
• different alpha/Lambda for isr and fsr
• implement switches PYTHIA/WHIZARD, settings etc.
• color connections in virtuality ordered ISR

[Juergen Reuter]

• parton_is_colored has to be replaced by a proper routine, in principle all parton_is_XXX routines.
• include SUSY colored objects

[Juergen Reuter]

Transferred to Gitlab issue 337.