Use some more underscores in showHSName Declaration instance

Makes it easier to read the generated names.
Ignore directories .cabal-sandbox and dist in Eclipse project

Prevents clutter when opening files with Control-Shift-r (or Command-Shift-r.)
Prefix database name by "ampersand_"
Groundwork for function-point analysis chapter (option --fpa)

The old --FPA option for generating an Excel workbook is renamed to --excel.
Set up basic infrastructure for function-point analysis

(Not integrated with the FSpec yet)
Move FPA computation to FPA.hs and refactor legacy FPA modules
FPA berekening geijkt met Frank Vogelenzang
Change type back to FPType

@stefjoosten: Does the cake rule apply to branches as well? :-)
Cleanup by having fpaDataModel return Maybe

@stefjoosten: FPA.fpaPlugInfo and Fspec2Excel.showDetailsOfPlug contain nice examples of pattern guards.
minor
Cleanup