Generated machine names can exceed length limits

webform_features_install() generates machine names based on node titles and form keys, without applying the self-imposed limits in accordance with the varchar storage. Note that node titles are varchar(255).

I couldn't see any particular reason to limit the machine names to such small values, so I propose that the fix allows the component names to have a limit as near to 255 chars as the calculation allows (if we allow the same maximum for each, plus the 2 char '__' separator, we can have up to 126 + 126 + 2 = 254).