Merge pull request sass#3027 from mgreter/bugfix/misc-segfaults

Fix a few segfaults

Merge pull request sass#2997 from mgreter/bugfix/2884-attribute-selec…

…tor-equality

Fix attribute selector equality (include modifier)

Merge pull request sass#2909 from glebm/ptr-comparison

Add comparison operators for SharedImpl, fix bugs

Delete extconf.rb

This file is unused, the Ruby gem is at sass/sassc-ruby

Update plugin test script to use precision 5

Revert "Upgrade sass2scss to version 1.1.2"

This reverts commit ca89d73.

This bump caused some regressions that are preventing implementors
from upgrading.

See sass#2637 sass#2638

Mentioned SharpScss and LibSassHost in implementations.md

Merge pull request sass#2586 from mgreter/feature/backtraces

Implement more detailed backtraces

Merge pull request sass#2559 from mgreter/bugfix/check-nesting-all-in…

…cludes

Enable nesting checks for all includes

Fix parsing of @supports declarations

Emulate the parse behaviour of `@media` query declarations.

Fixes sass#2452