With #29 we no longer generate broken signatures with FWS where they shouldn't be. However we could still improve our folding algorithm. Given these constraints:

• We want to be RFC-conformant (lines < 1000 chars)
• We don't want something too complicated (see Fix DKIM-Signature header flowing, it is not valid to arbitrarily sli… #27)
• Ensuring that lines are <75 chars is not necessary

We may want to fix these:

• We still don't properly fold h= params if they are very long
• We fold b= params at 75 chars, but we don't need to