Rewrite core functionality without using the difference crate

[dmerejkowsky]

Instead of just using string.replace or re.replace_all, actually do the work ourselves and compute a list of input and output fragments

Each fragment is a struct containing some text (either added or removed) and some position

This allows use to display the exact diff.

Implementation notes:

• Replace line_patcher module by just replacer

• Compute the list of patters and replacements much earlier (and just one) when using --subvert

• Also, implement Train-Case (also known as Http-Case) handling

• Display the patch while the source files are read. This means less shuffling of data around

• Tweak output

Old:

Patching foo/bar.js --- old is old +++ new is new

New:

foo/bar.js 3: old is old foo/bar.js 3: new is new

• We no longer allocate n*n bytes when patching a line of size 'n', so the fix for issue #52 is no longer needed

Fix #15

[dmerejkowsky]

I'm really proud of the new architecture. @tux3, would you mind taking a look and tell me what you think?

[dmerejkowsky]

Also, not really sure about the last commit ...

[tux3]

Also, not really sure about the last commit ...

I like it, but I'm maybe a little biased, if you listened to me you would have lifetimes everywhere =)

[cgestes]

Sorry didnt have much time to review. But I very much like the idea. Next step is to make a proper release and post on r/commandline and/or r/rust ? 😆

[dmerejkowsky]

Yeah - probably ;)

[cgestes]

Cool, I tried locally it works better than before :) Did my best to review, but haven't been written rust in a while.

[dmerejkowsky]

@cgestes I think I addressed all your feedbacks in 3e6a052

If that's ok with you, we can merge this :)