Undesired commit of whitespace changes

[DiThi]

Steps to reproduce:

• In a file make some change near the top.
• Then indent some block of code further down. In my case I indent with 4 spaces.
• Make some other change further down.
• In gittyup all 3 changes will show in the diff view, in separate hunks.
• In options -> diff, enable "Ignore Whitespace (-w)".
• In gittyup now two changes appear.
• Stage the top change only.
• Commit.

Expected result:

Only the staged change should have been committed.

Actual result:

Both the staged change and the whitespace change were commited. Note that the change doesn't appear in the diff view until you disable the option.

This is a problem particularly with languages with significant whitespace, where I didn't notice until after I made a bunch of other commits on top of it, and undoing it is very cumbersome.

Related: #603

(Ideally we should be able to ignore non-significant whitespace (anything that is not indentation), but that's probably a feature request for the git project, not a GUI.)

Gittyup version: 1.4.0, Arch Linux (gittyup-git package from AUR, commit is 28fa70a according to "About").