Implement a flexible cache system #28

Cache system should also be flexible for it's use in Pacstall's debug mode.

Database requirements

• Repo information including:
  • URL
  • Last update
  • List of packages
  • Preference order
• Pacscript information, including:
  • Name
  • Description
  • Homepage
  • Repology
  • Repository version (from last update)
  • Installed version
  • Auto/Manual
  • Dependencies (both apt's and pacstall's)
  • Optional dependencies (both apt's and pacstall's)
  • License (Requested here by @henryws)

Other requirements

• Source x Installed correlation
• Methods for safely adding and updating entries