Bump to version 0.4.1

Changelog:
* Transition to semantic versioning.
* e6b8bcf93faba52d0a340aee1bad86bf89178807: Fixed awkward wording in
readme.
* 5c0a9b16d89daf8f62b67ddf889abab065f261c7: Major update to the grid
system.
* 2ced138d3635a7ac7ad876f514fd3a40555f8551: Demo page update.

TODO:
* Complete the remaining columns.
* (Long-term) Working GitHub page with all the required docs.