STYLE: manage dictionary inputMode directly within entry class

- The logic for switching input-mode was previously completely
  encapsulated within the #inputMode directive, but without any
  programming equivalent. Furthermore, the encapsulation in inputMode
  made the logic less clear in other places.

  Exposing the inputMode as an enum with direct access from entry
  simplifies things a fair bit.

- eliminate one level of else/if nesting in entryIO.C for clearer logic

- for dictionary function entries, simply use
  addNamedToMemberFunctionSelectionTable() and avoid defining a type()
  as a static. For most function entries the information is only used
  to get a name for the selection table lookup anyhow.