By Luc Olinga Tesla’s billionaire CEO is resentful, never failing to remind his opponents of their past battles. Elon Musk rarely forgets. And Tesla’s (TSLA) – Get Tesla Inc. Report billionaire CEO certainly doesn’t forget those who have opposed him or his companies. To ensure they don’t keep a short memory, he reminds them of the disputes that have pitted them against each other. No schadenfreude here; he doesn’t revel in their difficulties. But he often does point out those difficulties, and sharply. Now, he has revived the rivalry with Henrik Fisker, the star automobile designer. In Februar…