Restore to revert

[sashadev-sky]

References #87 - add an img.revert() which reverts it to orig dimensions and rotation:

• I update the "Restore" action to "Revert", and updated the private method _restore to _revert (and updated README)

• Will have to be updated in MK (sorry will inline the svg in new PR asap)

• Pulled out from PR Matrix math and other code cleanups #339 as requested

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[sashadev-sky]

@jywarren this is ready for merge if you think so too!

[jywarren]

Nice!!!