don't check for the existence of a 'normalized file' if the file exists

[rvanheest]

Checking the existence of the 'normalized file' is quite expensive and often not necessary. This PR moves the call to existsNormalized() to a later point such that is isn't required to run if not necessary.

[jscancella]

@rvanheest I'm not sure the LoC actively maintains this anymore. I was the main author of this library and have forked it to continue maintaining it, check out https://github.com/jscancella/bagging

[rvanheest]

Hi @jscancella I'm aware of the inactivity of LoC on this library since you left. For this reason, we at @DANS-KNAW started a friendly fork for this library last year where we merged some of the available pull requests from last year. We deployed this version under our own groupId on Maven and have been using that fork ever since. Today I made the change in this PR on that fork and I thought I would contribute it to the main fork as well, as this change saves an O(n^2) magnitude of work in the validation process. I'll leave the PR open for LoC if they'd like to include it at some point. We'll continue on our own fork as long as LoC leaves this repository inactive.

[jscancella]

@rvanheest I too forked the repo and continued developing it adding new features and much more documentation. Please give it a try and provide any feedback you have https://github.com/jscancella/bagging