Safe Swap mod, improved Windows functionality

This release includes:

• a safer swap process which is less likely to void the existing card database on a phone
• better windows support around adb (this may cause more grief than anything, mind)
• improved UI feedback with SwingWorkers (faster logging in UI, better disabled states for buttons that shouldn't be clicked while a process is running)
• various code cleanups and documentation tweaks

Rough initial working version

Test on Mac and Windows:

• runs on Java SE 1.8 (java -jar DropmixModdingTool.jar)
• decompiles app (Mac, Windows)
• displays card data, playlist data (Mac, Windows)
• modifies sharedassets file (Mac, Windows)
• recompiles app (Mac, Windows)
• signs app (Mac, Windows)
• connects to android device via adb (Mac only, not verified)
• directly installs modified APK file (Mac only, not verified)

Known issues:

• entire card database needs to be freshly downloaded after each install (cards won't play audio otherwise). May investigate the potential of using the lower level card database instead (see level0mod branch) as I don't think it causes the same issues
• UI has major issues, likely needs multithreading to work around (this is worth adding anyway, I just wanted something functional out there)