TkN: prod branch

Data sources and content

• Adding new fission yields from the NUDAT source: 238U, 241Pu, and cumulative fission yields

tknucleus

• Adding the methods:
  • get_fission_yield(): returns fission yield for a given fissioning nucleus

GUI

• adding tools in the tknuclearchart to change the size and ratio of the plot, and width of the magic numbers

tklevel_scheme

• correction of a bug in the method [get_decay()](const shared_ptr<T> get_decay(const tkstring &_name, bool _exact)) to catch negative parity states

tknucleus

• adding tokenize_from_string() method to tokenize from a full string

General

• adding specific files (thistkn.zsh and tkn-autocompletion.zsh) for zsh shells