Opt install location and Legacy Icons

New variant added that installs to the /opt folder instead of .local.
Makes it much faster to access the Firefox folder if you tend to make a lot of tweaks like me. This variant isn't made for multi user systems, as only the person who runs the script will have permissions to the folder, preventing other users from updating. Hence the multi user install script isn't included. Use the main script if your system has multiple user accounts on it.

Also included is a legacy icon folder, containing a version of the Firefox logo before Mozilla's controversial redesign. Rename it to replace the regular icons folder before installing if you want to use it.