Fix building under Xcode 10.2.x

[tonyarnold]

This PR is a redo of #63. I'd like to do this in a bunch of smaller stages, but this first one is unavoidably a large PR.

Notes

Please merge #70 before this PR, as this PR contains the contents of fix/crash-on-start as well.

Changes

• CocoaPods has been switched out for Carthage (sorry, I just can't handle the magic ✨ )
• CocoaLumberjack has been replaced with Apple's Universal Logging (OSLog)
• Deployment target has been bumped to macOS 10.14
• Converted overridden NSObject.hashValue methods to NSObject.hash
• Various smaller project fixes:
  • Bump project format to Xcode 10.0 / objectVersion 51
  • Move COMBINE_HIDPI_IMAGES to be a project-level setting
  • Explicitly set the project indents to 4 spaces (this seems to be the project default, it just wasn't being enforced)

[bellebethcooper]

Swapping Cocoapods for Carthage is a personal preference change, so it makes more sense to have your own fork for that as I prefer Cocoapods. Regardless, I'm going to archive this repo as I'm not actively working on it anymore, but please feel free to maintain your own fork to pull all these changes into if you'd like to keep using the app :)