updated to {sf} and R >= 4.2.0

[gsapijaszko]

Hi,

most changes:

• package adopted to R >= 4.2.0
• {rgdal}, {rgeos} and {sp} replaced with {sf} (it addresses the rgdal to sf transition #5 )
• added grid = FALSE | TRUE parameter, which sets the flying direction over polygon
• incorporated most changes from @Hivemapper (see: Hivemapper features #4 )

Package was extensively tested by @merkato.

Regards,
Grzegorz