Separate brew & brew cask forumlae

NB:
- alos update brewfile:
  `brew leaves | sed 's/^/install /' > Brewfile`
- macivm need special handling
Add custom "ctrlp" configuration

Seems it’s needed to correctly parse the .gitignore that have rules to
complement the parent’s folder’s .gitignore
Make some settings for zsh to be platform-specific
Add plugin for more colour schemes in vim