Unconditionally activate the occur stuff in ledger-occur-mode
Unconditionally activate the occur stuff in ledger-occur-mode

Well, we still deactivate it when regex is nil, but the function
should not look at previous value of ledger-occur-mode:

- the interactive function (ledger-occur) already do it, we don't need
  to do it there,
- caller that want to deactivate the occur stuff only have to call
  ledger-occur with a nil regex
- the old behavior make ledger-reconcile to turn off occur stuff if it
  was already turn on, when what we do want is that the occur stuff
  change to the new account.

jwakely/ledger,jwakely/ledger,paulbdavis/ledger,paulbdavis/ledger,paulbdavis/ledger,afh/ledger,duncanmortimer/ledger,jwakely/ledger,afh/ledger,paulbdavis/ledger,duncanmortimer/ledger,afh/ledger,duncanmortimer/ledger,ledger/ledger,duncanmortimer/ledger,jwakely/ledger,ledger/ledger,duncanmortimer/ledger,ledger/ledger,ledger/ledger,afh/ledger,paulbdavis/ledger,jwakely/ledger,jwakely/ledger,duncanmortimer/ledger,paulbdavis/ledger,paulbdavis/ledger,jwakely/ledger,duncanmortimer/ledger,ledger/ledger,afh/ledger