Fix CreateFileW function usage, otherwise it fails to open file.
Merge pull request #501 from vadimi/master

Fix CreateFileW function usage, otherwise it fails to open file.
Fixes build to report correctly to coveralls.io
Accept multiple - characters before interpolant
Merge pull request #503 from mgreter/feature/coveralls-metrics

Fixes build to report correctly to coveralls.io
Merge pull request #504 from carsonmcdonald/fixfor478

Accept multiple - characters before interpolant
Straightens out some sass_interface api issues

Moved `source_map_file` from context to options.

Fix for `omit_source_map_url` (propagate to cpp_ctx).

Removed superfluous `source_maps` from struct, generate
source maps when `source_map_file` string contains data.
Merge pull request #505 from mgreter/fix/sass_interface_api

Straightens out some sass_interface api issues