First version (fairly complete) to generate the Run 3 L1 Menu. Main
points:
* The L1Menu and L1TopoMenu have been merged
* There are three directories:
  - L1/Menu for the menu definition
  - L1/Config for the threshold and item definition and cabling layout, and
  - L1/Base for classes to hold the menu in place

Start assembling an MC_pp_v8 menu. The menu remains split into 2 files,
a file Menu_x that defines the items, and a file Menu_x_inputs, which
defines the configuration of the topo boards, muctpi and ctpin. A third
Menu file exists for the legacy inputs.