Misc: Drop support for older browsers; update support comments

That includes IE<8, Opera 12.x, Firefox<29, Safari<6.0 and some hacks
for old Blackberry.

Fixes gh-1836
Fixes gh-1701
Refs gh-1815
Refs gh-1820
I understand `11+` as "For sure `11` but maybe even `12` or larger". If you put it in this context then `IE<11+` would mean "IE older than 11 (i.e. IE10 or older) but maybe even IE older than 12 (i.e. IE11 as well) or larger" which is not what we claim here as IE11 is affected here.