Fixes #292

Use djb2 to hash the entire css property. A test case using known-css-properties has been added to make sure there is no collision.

The bundle size before the change:

index.js → dist/umd/stylis.js...
 stylis.js ⏤  4.11 kB

created dist/umd/stylis.js in 385ms

index.js → dist/stylis.mjs...
 stylis.mjs ⏤  3.97 kB

The bundle size after the change:

index.js → dist/umd/stylis.js...
 stylis.js ⏤  4.54 kB

created dist/umd/stylis.js in 378ms

index.js → dist/stylis.mjs...
 stylis.mjs ⏤  4.41 kB
created dist/stylis.mjs in 388ms

It is 500 bytes larger (after gzip).

Mark the PR as a draft for further discussion.

Potential optimization: use toString(36) or a self-implemented toString(62)?