Do not encode cookie name

Problem/Motivation

JS does not urlencode cookie names as I thought earlier, and it is actually able to read non-encoded cookies, like styleswitcher[theme_name]. I can't even recall how I came to opposite conclusion when explicitly made encoding in styleswitcher_save_user_preference().

Tests shown that plain styleswitcher[theme_name] cookie is OK for both JS & PHP.

Proposed resolution

Decode the cookie name.