Obsolete version of ngraph.forcelayout as dependency

The problem is that according to the `package.json` -file, the library requires `ngraph.forcelayout` to be of the version `^1.2.0`, so by default it installs aforementioned package of the version `1.2.0`. Version `1.2.0` of `ngraph.forcelayout` though doesnt split functions that calculate the node mass into `defaultArrayNodeMass` and `defaultSetNodeMass`. Instead, there is only one function called `defaultNodeMass`. That function cant calculate the length of the set `links` properly because it refers to the `length`-attribute, not to the `size`. Therefore, e.g. in my case by executing the function `createLayout`, which is provided by `ngraph.offline.layout`-library I receive the following error: `Error: Node mass should be a number`. I assume that this issue can be neutralized by updating the version of `ngraph.forcelayout` at the package.json to the one, where this function is able to calculate the size of the set properly.

Start with package.json to inspect the ngraph.forcelayout dependency, then reproduce the reported createLayout failure from ngraph.offline.layout. Confirm which dependency version handles set size correctly; done means the dependency is updated and createLayout no longer raises the node-mass error.

Written by the indexing model from the issue text.