add possibility to write metadata in the templates

[zhakk-harn]

authors
difficulty
semver
symlink

[zhakk-harn]

enable "symlinking", allowing one template to be in multiple tech while remaining in one folder

[zhakk-harn]

use version in the same way dockerfiles do

[zhakk-harn]

should be able to link to a local static library which the template depend on.
The idea is to then have local versions of libraries when we can't depend on a global package repository (e.g. if we get to have multiple templates depending on ml5.js we should have just one copy on the repo and have the template pull it after getting pulled)

this way we get to have mainstream use of a version across templates and we're not depending on a distribution system other than github (but if we're using github it safe to assume we have atleast 2-3 back up on our end)

[zhakk-harn]

next step would be to dowload and save them along with the preferences.json (probably in ~/.fido/) but then, how to we link them from this global dependencies to the templates?