Autosuggest for variables containing dashes doesn't work

The 'extract_completions' method seams to have a bug when it comes to variables that contain one or more dashes.

Testcase

$button_color_main: #0f0 /* works as expected */

$button-color-secondary: #f00 /* will auto complete only the word '$button' */

The bug is double checked and confirmed, more here: https://github.com/alienhard/SublimeAllAutocomplete/issues/18