Add support for multi-asset fetching

[bladealslayer]

Don't merge until release and keep the branch on top of master.

TODO:

• remove build before merging for release

Two new SDK fns: assetsByAlias() and assetsByVersion().

[rap1ds]

LGMT, commented something about the longest path algo

[lyyder]

Looks good. Check also the error message on line 351, in the asset by version request, that was not updated in this PR, there seems to be 'alias' instead of 'version':

      if (!version) {
        throw new Error('Missing mandatory parameter `alias`');
      }

[rap1ds]

Whou I did not know you can do destructions like this. TIL!

[walterrw]

Just learned it also while I was doing this 😀

[bladealslayer]

I love that typo / autocorrect :)