isBreakpoint Helper

Read about it here - https://code.area17.com/a17/a17-helpers/wikis/isBreakpoint

Basically you pass in a breakpoint and it tells you whether it is active or not. It supports the +/- modifiers.

The breakpoint names are hardcoded but they're what we use on all projects (even if we remove some). Any ideas how we could store and load this from the manifest.json?