* 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
