History save/load/purge throws IOException

[Jason Dillon]

Guillaume,

Howdy, I ran into some minor issues while transitioning to jline3 related to on-disk history format being different than jline2.

Wondering about this change to expose the IOException:

https://github.com/jline/jline3/pull/118/commits/13b6249455f3126f1603df2e5fd72223c331e5ea

… so that calling api might be made aware of the issue.

FTR it does seem generally sane-ish to expose these, though due to the nature of how history impl works presently in terms of getting its file from the LineReader and attach() calling load() it may still not be enough to allow an app to maybe more quietly automatically purge() invalid history without additional changes.

But before I go farther wondering about generally adding the throws IOException to these 3 methods.

—jason