NEP-PACK 0.2.0-rc1

This is a major rewrite of NEP-PACK, including (but not restricted to)

• More and better methods (e.g. jd, nleigs, restarting in nlar, )
• More efficiency (e.g. type stability)
• More native benchmark problems
• Better documentation
• Support for other NEP-types (e.g. SumNEP)