Installation for remote packages hosted on git repositories.

[novacbn]

gmodproj add <...packages> - Adds and installs new dependencies.

Proposed gmodproj add workflow:

• gmodproj clones the package repository.
  • commit hashes and semver commit tags can be specified e.g. gmodproj add 1.0.0@git://my.domain/package
• Reads the package's .gmodmanifest and stores the package's source code within CACHE/PROJECTAUTHOR/PROJECTNAME/COMMITHASH for later installations
• Clones package from gmodproj's cache by commit hash into project's packages folder as packages/PROJECTAUTHOR/PROJECTNAME
• Stores package by commit hash, commit tag(if applies), and url in .gmodpackages.
• Alias for GitHub based repositories via github://USERNAME/PROJECTNAME

Proposed gmodproj install workflow:

• Read project's .gmodpackages file and installs all uninstalled repositories.