When using toAbs for all but the most trivial cases, one needs access to
the options. Unlike measurements which are always there, options aren't
always set since they are only set when they differ from the default.
This would shift a lot of responsibility on the pattern designer who
would have to check whether an option is set, and if it's not use the
default which in turn depends on what type of an option it is (and it's
pct for example you have to remember to divide it by 100 and so on).
This feels footgun-y so instead I've added a `mergeOptions` method that
merges the options passed by the user with the defaults from the pattern
config so that you have a simple object with all option values.
This should get passed to `toAbs()` as the 3rd parameter.
