* misc
- cleanup of old release notation in comments: e.g. if it's not applicable to ESR78+
- same with default version info
- simplify and save bytes on section 4700
- update 4500 header
- and unify the message about using extensions as counterproductive
- letterboxing
- provide info on stepped ranged (and drop crap about FF67)
- don't judge users who dislike seeing margins (I don't like them either, but I force my window to exact dimensions and stay there)
- screenshots uploading was disabled in FF67+ : [67 release notes](https://www.mozilla.org/en-US/firefox/67.0/releasenotes/)
- the pref is still there (default false) but so far I'm 99% sure this pref now does anything
- I will add it to the scatchpad script if this change sticks
* simplify 4500 RFP, see #1041
* update removed script
* tidy readme, see #1045
- also put readme before releases
* RIP FX Site Compat
* clean out RFP Alts info: the information is redundant: it's already in the readme
- make 1401 inactive: it affects RFP's FPing
- remove old warning/setup-web: we do not care about documenting breakage or FPing risks when we have a warning and they are inactive. If someone uses them, that's on them
- new warnings
- this was made inactive in v68
- since at least FF79, when active as false, it breaks the web and browser consoles
- it breaks websites
- it breaks extensions: e.g. uBO panel functionality
- it does nothing to mitigate possible fingerprinting (which was why it was initially added as a concern) - i.e the API only provided a standardized method, it does not stop previous/earlier workarounds
* 0 : successful termination
* 2 : command line syntax error
* 1 : catchall for general errors
Plus a few text improvements based on unmerged PR 4fbb2be98d
- less active prefs
- now that ESR68 is EOL, at least a whopping two (0602, 1273)
- also I don't know when the default changed - another whopping whole one (1240)
- and where we do enforce/reset a pref to default, lets say that
- this is not a definitive list, sing out if there is anything else
- IPv6 info
- especially for Iron Heart who likes to claim that this pref breaks 5% of sites
- cleanup of settings tags now we only care abut ESR78+
