“Springboard relief is not intended to punish the defendant for wrongdoing. It is merely to provide fair and just, and proportionate protection against ongoing harm resulting from the wrongdoing, whilst that unlawful harm lasts. What is fair and just in any particular circumstances depends on (1) the effect of the unlawful acts upon the claimant; and (2) the extent to which the defendant has gained an illegitimate competitive advantage. The appropriate measure for the length of a Springboard injunction is the length of time that it would have taken the wrongdoer to achieve lawfully what he in fact has achieved unlawfully, relative to the claimant. Its purpose is to put the parties back into the position they would have been in had there not been the past misuse of confidential information or wrongdoing, through putting the defendant at a special disability for a period to ensure that the defendant does not obtain an unfair start over the claimant”