Vroom vroom

Breaking

Revert changes to raw CSS @imports

Due to unintended disruption this change has been reverted in favour of a language level revision to CSS imports to be implemented at a future date.

Note to implementors: this removes the sass_option_push_import_extension API added in 3.5.4. Apologies for the disruption.

Deprecations

• Add deprecation messages for colour arithmetic (@xzyfer, #2414)

Features

• Support hex colors with alpha channels (@xzyfer, #2674)
• Add a sass_option_push_import_extension C-API (@xzyfer, #1964)

Fixes

• Fix segfault in handling modulo operator (@xzyfer, #2659)
• Fix handling of unclosed interpolant in url (@xzyfer, #2661)
• Fix possible bug with handling empty reference combinators (@xzyfer, #2665)
• Fix -Wmissing-declarations for gcc < 7 (@xzyfer, #2690)