Adding of the NRC Affect Intensity Lexicon

There are more lexicons available that can be potentially added to the website.

For example, the **NRC-Affect Intensity** Lexicon By Dr. Saif M. Mohammad

The work can be obtained [here](https://saifmohammad.com/WebPages/AffectIntensity.htm).

If this can be added to the current lexicons it would be great. The structure of the project should be easy to understand and extend.

References

1. [Word Affect Intensities.](https://arxiv.org/abs/1704.08798) Saif M. Mohammad. In Proceedings of the 11th Edition of the Language Resources and Evaluation Conference (LREC-2018), May 2018, Miyazaki, Japan.
[Paper (pdf)](https://saifmohammad.com/WebDocs/lrec2018-paper-word-emotion.pdf)

If any help is needed, feel free to ask.

Review the project's existing lexicon structure and the NRC-Affect Intensity source linked in the issue. Add the lexicon to the website's available lexicons and verify that it is included and usable alongside the current sentiment resources.

Written by the indexing model from the issue text.