Author: Dan Poltawski
MDL-56488 boost: validate scss settings for parsable scss
* Parses the scss and fails validation if a parse error is found
* Does not detect the situation when variables are not present - this
would involve us parsing the entire tree and would be slow. It could
also change over time, depending on whats defined in the scss
from themes.
* Introduces a new admin_setting_scsscode to do this
http://git.moodle.org/gw?p=moodle.git;a=commit;h=0e34e46fd047abcb797aa8c950f80bf30ef53af9
http://github.com/moodle/moodle/commit/0e34e46fd047abcb797aa8c950f80bf30ef53af9
+ 3.3 en [scssinvalid,core_admin]