Sass partials depend on their parents files for context. This patch disables the
syntax checking for partials by default because of this. To enable checking of
partials let g:syntastic_sass_check_partials = 1. Fixes issue #300.
Only cache the imports when the syntax checker is first loaded. Also,
there was a bug in the logic that was causing the imports to be set to
"" on the second run.
Make the imports var script local since we are not allowing users to
change it.
We dont need to manually hack the bufnr for each entry in the loc list
since that the error output includes a file name.
Ignore the last line of the error message since it seems to always just
be "use --trace for a backtrace"
