Log Message:
Changes 3.3.6:
Expose the Sass language version via the C API

Fixes:
Incorrectly erring on comments in at-rules
Incorrectly dropping internal state of AST nodes
Incorrectly parsing the calc function
Segfault during error handling
Incorrectly identifying the selectors with type-of
Incorrectly erring on ID selectors starting with a number
Producing incorrect output when compile with MSVC
Various segfaults and incorrect output from @extend