v3.0.0

FINUFFT v3.0.0

Diff since v2.1.0

Closed issues:

• Thread-safety (#28)
• on recovering FFTW result? (#30)
• finufft_setpts should be finufft_setpts! (#34)
• finufft_destroy crashes Julia (#35)

Merged pull requests:

• Add guru interface and single/double precision calling interface (#33) (@lulibin)
• Release v3.0 and fix CI for newer Julia versions (#37) (@ludvigak)